Quadratic Sequences: The Nth Term of a Quadratic Number Sequence
Here, we will be finding the nth term of a quadratic number sequence. A quadratic number sequence has nth term = an² + bn + c
Example 1
Write down the nth term of this quadratic number sequence.
-3, 8, 23, 42, 65...
Step 1: Confirm the sequence is quadratic. This is done by finding the second difference.
Sequence = -3, 8, 23, 42, 65
1st difference = 11,15,19,23
2nd difference = 4,4,4,4
Step 2: If you divide the second difference by 2, you will get the value of a.
4 ÷ 2 = 2
So the first term of the nth term is 2n²
Step 3: Next, substitute the number 1 to 5 into 2n².
n = 1,2,3,4,5
2n² = 2,8,18,32,50
Step 4: Now, take these values (2n²) from the numbers in the original number sequence and work out the nth term of these numbers that form a linear sequence.
n = 1,2,3,4,5
2n² = 2,8,18,32,50
Differences = -5,0,5,10,15
Now the nth term of these differences (-5,0,5,10,15) is 5n -10.
So b = 5 and c = -10.
Step 5: Write down your final answer in the form an² + bn + c.
2n² + 5n -10
Example 2
Write down the nth term of this quadratic number sequence.
9, 28, 57, 96, 145...
Step 1: Confirm if the sequence is quadratic. This is done by finding the second difference.
Sequence = 9, 28, 57, 96, 145...
1st differences = 19,29,39,49
2nd differences = 10,10,10
Step 2: If you divide the second difference by 2, you will get the value of a.
10 ÷ 2 = 5
So the first term of the nth term is 5n²
Step 3: Next, substitute the number 1 to 5 into 5n².
n = 1,2,3,4,5
5n² = 5,20,45,80,125
Step 4: Now, take these values (5n²) from the numbers in the original number sequence and work out the nth term of these numbers that form a linear sequence.
n = 1,2,3,4,5
5n² = 5,20,45,80,125
Differences = 4,8,12,16,20
Now the nth term of these differences (4,8,12,16,20) is 4n. So b = 4 and c = 0.
Step 5: Write down your final answer in the form an² + bn + c.
5n² + 4n
Questions & Answers
Find the nth term of this sequence 4,13,28,49,76?
The first differences of this sequence are 9, 15, 21, 27, and the second differences are 6.
Since half of 6 is 3 then the first term of the quadratic sequence is 3n^2.
Subtracting 3n^2 from the sequence gives 1 for each term.
So the final nth term is 3n^2 + 1.
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Find the nth term of this sequence 2,9,20,35,54?
The first differences are 7, 11, 15, 19.
The second differences are 4.
Half of 4 is 2, so the first term of the sequence is 2n^2.
If you subtract 2n^2 from the sequence you get 0,1,2,3,4 which has the nth term of n - 1
Therefore your final answer will be 2n^2 + n - 1
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What is the ninth term of this sequence 6,12,20,30,42,56?
The first differences are 6,8,10,12,14. The second difference is 2. Therefore half of 2 is 1 so the first term is n^2. Subtract this from the sequence gives 5,8,11,14,17. The nth term of this sequence is 3n + 2. So the final formula for this sequence is n^2 + 3n + 2.
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Find nth term of this sequence 10,33,64,103?
The first differences are 23, 31, 39 and the second difference is 8.
Therefore since half of 8 is 4 the first term will be 4n^2.
Subtracting 4n^2 from the sequence gives 6, 17, 28 which has nth term 11n - 5.
So the final answer is 4n^2 + 11n -5.
Helpful 21Can you find the nth term of this sequence 5,16,33,56?
The first differences are 11, 17, 23, and the second differences are 6.
Half of 6 is 3, so the first term is 3n^2.
Subtracting 3n^2 from the sequence gives 2, 4, 6, 8 which has nth term 2n.
So the final formula for this quadratic sequence is 3n^2 + 2n.
Find the nth term of this 2, 17, 40, 71?
The fist differences are 15, 23, 31, and the second difference are 8.
Since the second difference are 8, then the first term of the nth term is 4n^2 (Half of 8).
Subtracting 4n^2 from the sequence gives -2, 1, 4, 7, which has nth term 3n -5.
So the final answer is 4n^2 + 3n -5.
Helpful 4Find the nth term of this sequence 0,6,18,36,60?
First, work out the first differences; these are 6, 12, 18, 24.
Next, find the second differences, these are all 6.
So since half of 6 is 3, then the first term is 3n^2.
Subtracting 3n^2 from the sequence gives -3, -6, -9, -12, -15 which has nth term of -3n
So the nth term of this quadratic sequence is 3n^2 - 3n.
Helpful 2Can you find the next term in the sequence 4,12,24,40?
The first differences are 8, 12, 16, so the next difference will be 20 as the first differences are increasing by 4. Therefore the next term is 40 + 20 = 60.
Helpful 5What is the nth term rule of the sequence -8, -8, -6, -2, 4?
The first differences are 0, 2, 4, 6, and the second diffferences are all 2.
Since half of 2 is 1, then the first term of the quadratic nth term is n^2.
Next, subtract n^2 from the sequence to give -9,-12,-15,-18,-21 which has nth term -3n - 6.
So the nth term will be n^2 -3n - 6.
Helpful 5Can you find the nth term of 10,24,44,70,102,140?
First work out the first differences, these are 14, 20, 26, 32, 38
Next find the second differences, these are all 6.
So since half of 6 is 3, then the first term is 3n^2.
Subtracting 3n^2 from the sequence gives 7, 12, 17, 22, 27 which has nth term of 5n + 2.
So the nth term of this quadratic sequence is 3n^2 + 5n + 2.
Helpful 1Find the nth term of this sequence 8,16,26,38,52,68,86 ?
The first differences are 8, 10,12,14,16,18 and the second differences are 2.
Half of 2 is 1, so the first term of the formula is n^2.
Subtracting n^2 from the sequence gives 7,12,17, 22, 27, 32 which has nth term 5n + 2.
Therefore, the final nth term is n^2 + 5n + 2.
Find the nth term of this quadratic sequence below? 6,20,40,66,98,136
The first differences are 14, 20, 26, 32, 38, and the second differences are 6.
Half of 6 is 3, so the nth term is 3n^2.
Subtracting 3n^2 gives 3, 8, 13, 18, 23, 28 which has nth term 5n - 2.
Therefore the nth term is 3n^2 + 5n - 2.
Find the nth term of -2,1,6,13,22,33?
These numbers are 3 smaller than the square numbers so the formula is n^2 - 3.
Can you find the nth term of this quadratic sequence 4,7,12,19,28?
The first differences are 3, 5, 7 and 9, and the second differences are 2.
Therefore the first term will be n^2 (half of 2 is 1).
Subtracting n^2 from the sequences gives 3.
So the final answer is n^2 + 3.
Helpful 3What is the sequence of n^2?
n^2 is just the square number sequence 1,4,9,16,25,36,49...
What is the nth term for -8,-8,-6,-2,4,12,22 ?
The first differences are 0, 2, 4, 6, 8, 10 and the second differences are 2.
Since half of 2 is 1 then the first term is n^2.
Subtracting n^2 from the sequence gives -9, -12, -15, -18, -21, - 24, -27 which has nth term -3n - 6.
So putting this together gives n^2 - 3n - 6.
Find the nth term of 15, 23, 33, 45, 59?
The first differences are 8, 10, 12, 14, and the second differences are 2.
This means the first term is n^2.
Subtracting n^2 from this sequence gives 14, 19, 24, 29, 34 which has nth term 5n + 9.
So the final answer is n^2 + 5n + 9.
Find the nth term of this sequence 1,10,25,46,73,106?
The first differences are 9, 15, 21, 27, 33 and the second differences are 6.
Half of 6 is 3, so the first term of the formula is 3n^2.
Subtracting 3n^2 from the sequence gives -2.
Therefore, the final nth term is 3n^2 - 2.
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Can you find the nth term of 11, 26, 45 and 68?
The first differences are 15, 19 and 23. The second differences are 4.
Half of 4 is 2, so the first term is 2n^2.
Subtracting 2n^2 from the sequence gives you 9, 18, 27 and 36, which has nth term 9n.
So, the final formula for this quadratic sequence is 2n^2 + 9n.
Helpful 14What is the nth term of this: 3,18,41,72,111?
The first differences are 15,23,31,39, and the second differences are 8.
Halving 8 gives 4, so the first term of the formula is 4n^2
Now subtract 4n^2 from this sequence to give -1,2,5,8,11, and the nth term of this sequence is 3n – 4.
So the nth term of the quadratic sequence is 4n^2 + 3n – 4.
Helpful 14Find the nth term of this sequence 3,8,15,24?
The first differences are 5, 7, 9 and the second differences are 2.
Therefore the first term of the sequence is n^2.
Subtracting n^2 from the sequence gives 2,4,6,8 which has nth term 2n.
So the final answer is n^2 + 2n.
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What is the nth term of 6, 20, 40, 66, 98,136?
The first differences are 14, 20, 26, 32 and 38, and so the second differences are all 6.
Halving 6 gives 3, so the first term of the sequence is 3n^2.
Subtracting 3n^2 from the sequences gives 3,8,13,18,23 which has the nth term 5n-2.
Therefore, the formula for this sequence is 3n^2 + 5n - 2.
Helpful 9What is the nth term rule of the quadratic sentence? -7,-4,3,14,29,48
The first differences are 3,7,11,15,19 and the second differences are 4.
Halving 4 gives 2, so the first term of the formula is 2n^2.
Now subtract 2n^2 from this sequence to give -9,-12,-15,-18, -21, -24 and the nth term of this sequence is -3n -6.
So the nth term of the quadratic sequence is 2n^2 – 3n – 6.
Helpful 8Can you find the nth term of this sequence 8,16,26,38,52?
The first difference of the sequence are 8, 10, 12, 24.
The second differences of the sequences are 2, therefore since half of 2 is 1 then the first term of the sequence is n^2.
Subtracting n^2 from the given sequence gives, 7,12,17,22,27. The nth term of this linear sequence is 5n + 2.
So if you put the three-term together, this quadratic sequence has the nth term n^2 + 5n + 2.
Helpful 7Can you find the nth term of the quadratic sequence 3,8,17,30,47?
First work out the first differences, these are 5, 9, 13, 17.
Next, find the second differences, these are all 4.
So since half of 4 is 2, then the first term is 2n^2.
Subtracting 2n^2 from the sequence gives 1, 0, -1, -2, -3 which has nth term of -n + 2.
So the nth term of this quadratic sequence is n^2 -n + 2.
Helpful 6What’s is the nth term of this: -4,1,12,29?
The first differences are -5, -11, -17, and so the second differences are all 6.
Halving 6 gives 3, so the first term of the sequence is 3n^2.
Subtracting 3n^2 from the sequences gives -7,-11,-15,-19 which has the nth term -4n-3.
Therefore, the formula for this sequence is 3n^2 -4n - 3.
Helpful 6Can you find the nth term of this sequence 2,5,10,17?
The first differences are 3, 5, 7 and the second difference are 2.
Since the second differences are 2, then half of 2 is 1, so the first tem of the sequence is n^2.
Subtracting n^2 from this squences gives 1,1,1,1.
So the nth term of this quadratic sequence is n^2 + 1.
Helpful 6What is the nth term of this question? 2, 6, 18, 54...
This is not a quadratic sequence, but a geometric one.
The nth term is 2.3^(n-1).
Helpful 2What is the nth term rule of the quadratic sequence: 6, 12, 20, 30, 42, 56, 72?
The first differences are 6, 8, 10, 12, 14, 16 and so the second differences are all 2.
Halving 2 gives 1, so the first term of the sequence is n^2.
Subtracting n^2 from the sequences gives 5,8,11,14,17, 20 which has the nth term 3n + 2.
Therefore, the formula for this sequence is n^2 + 3n + 2.
Helpful 3Find the nth term of this sequence 5,9,21,41?
The first differences are 4, 12, 20.
The second differences are 8.
Therefore, since 1/2 of 8 = 4, then the first term of the quadratic sequence is 4n^2.
Subtract 4n^2 from the sequence gives 1, -7, -15, -23 and the nth term of the linear sequence is -8n + 9.
Hence the nth term of this quadratic sequence is 4n^2 -8n + 9.
Helpful 5Can you find the nth term of this sequence 8,16,26,38,52,68,86?
The first differences are 8,10,12,14,16,18 and the second differences are 2.
Since half of 2 is 1, then the first term of the nth term is n^2.
Subtracting n^2 from the sequence gives 7,12,17,22,27,32,37 which has a nth term of 5n + 2.
So putting these together gives a nth term of the quadratic sequence of n^2 + 5n + 2.
Helpful 5Can you find the nth term of this sequence 4,7,12,19,28?
The first difference are 3, 5, 7 and 9. The second differences 2, so the first term is n^2 (since half of 2 is 1).
Subtracting n^2 from the sequence gives 3.
So the nth term of this quadratic sequence is n^2 + 3.
Helpful 5Can you find the nth term of 2,17,40,71?
The first differences are 15, 23, 31, and so the second differences are all 8.
Halving 8 gives 4, so the first term of the sequence is 4n^2.
Subtracting 4n^2 from the sequences gives -2, 1, 4, 7 which has the nth term 3n - 5
Therefore, the formula for this sequence is 4n^2 + 3n - 5.
Helpful 4Is the number 174 in the sequence n²+5?
Make n^2 + 5 = 174.
Subtract 5 from both sides to give n^2 = 169.
Then square root both sides to give n = 13.
174 is the 13th term in the sequence, so yes.
Helpful 4How would I find the nth term of this sequence: 4, 7, 12, 19, 28?
First find the first differences to give 3, 5, 7, 9 and therefore the second differences are 2.
This means the first term will be n^2 as half of 2 is 1.
Subtracting n^2 from the sequence gives 3.
So the final formula for the sequence is n^2 + 3.
Helpful 4What are the next 3 terms of 26,37,50?
Assuming that the sequence is quadratic the first difference are 11 and 13. So the first differences are increasing by 2 each times.
So the fourth term will be 50 + 15 = 65.
The fifth term will be 65 + 17 = 82.
The sixth term will be 82 + 19 which is 101.
Helpful 4How can you work out the nth term for this quadratic sequence 6, 10, 16, 24, 34?
The first differences are 4,6,8,10, and the second differences are 2 giving the first term of n^2.
Subtracting n^2 from this sequence gives 5,6,7,8,9 which has nth term of n + 4.
So the nth term of this quadratic sequence is n^2 + n + 4.
Helpful 4What is the nth term rule of the quadratic sequence: -5,-4,-1,4,11,20,31?
The first differences in the sequence are 1, 3, 5, 7, 9, 11 and the second differences are all 2.
Halving that equals 1, so the first term of the sequence is n^2.
Subtracting n^2 from the sequence gives -6, -8, -10, -12, -14, -16, -18, which has nth term -2n - 4.
So the final answer is n^2 -2n - 4.
Helpful 4How would I find the nth term of this sequence 2,10, 24, 44?
The first differences are 8, 14, 20 and the second difference is 6.
Since half of 6 gives 3, the first term of the sequence is 3n^2.
Subtracting 3n^2 from this sequence gives -1, -2, -3, -4, which has a nth term of -n.
Therefore putting this together gives an answer of 3n^2 -n.
Helpful 4What is the nth term of the sequence 0,3,8,15,24?
These numbers are one smaller than the square number sequence, so it will be n^2 - 1.
Helpful 1How can I find the 12th term of this sequence 13, 24, 35, 46, 57?
The sequence is a linear sequence not quadratic increasing by 11 each time.
Since you only want the 12th term it will be easier just to continue the sequence by adding on 11 each time.
13,23,35,46,57,68,79,90,101,112,123,134.
So the 12th term is 134.
Find the nth term of this sequence 6,17,34,57,86?
The first differences are 11, 17, 23, 29, and the second differences are 6.
Since half of 6 is 3, then the first term will be 3n^2.
Subtracting 3n^2 from the sequence gives 3, 5, 7, 9, 11 which has nth term 2n + 1.
Therefore the final answer is 3n^2 + 2n + 1.
What is the nth term of this quadratic number sequence: 1,3,6,10,15?
The first differences are 2,3,4,5 and the second differences are 1.
Therefore the first term in the quadratic sequence is 0.5n^2.
Subtracting 0.5n^2 from the sequence gives 0.5, 1, 1.5, 2, 2.5, and the nth term of this linear sequence is 0.5n.
So the final answer of this sequence is 0.5n^2 + 0.5n.
Helpful 3Find the nth term for the quadratic sequence of 3,9,17,27?
The first differences are 6 8,10 and the second differences are 2.
The first term of the sequence is therefore n^2 (since half of 2 is 1).
Subtracting n^2 from the sequecne gives 2, 5, 8, 11 which has the nth term of 3n - 1.
So putting the 3 terms together gives a final answer of n^2 + 3n - 1.
Helpful 3Find the nth term if this sequence 8,16,26,38,52,68,86?
The first differences are 8,10,12,14,16,18, and the second differences are 2, so the first term will be n^2.
Subtracting n^2 from the sequence gives 7,12,17,22,27,32,37 which has nth term of 5n + 2.
So the final answer is n^2 + 5n + 2.
Helpful 3What is the nth term of -4,-1,4,11,20,31?
The first differences are 3, 5, 7, 9, 11 and the second differences are all 2, so the sequence must be quadratic.
Half of 2 gives 1, so the first term of the nth term is n^2.
Subtracting n^2 from the sequence gives -5.
So putting both terms together gives n^2 -5.
Helpful 3How can I find the next terms of this sequence 4,16,36,64,100?
These are the even square numbers.
2 squared is 4.
4 squared is 16.
6 squared is 36.
8 squared is 64.
10 squared is 100.
So the next term in the sequence will be 12 squared which is 144, then the next one 14 squared which 196 etc.
Helpful 3What is the nth term of this quadratic sequence : -4,1,12,29,52,81?
The first differences are 5, 11, 17, 23, 29, and the second differences are 6.
Halving 6 gives 3, so the first term will be 3n^2.
Subtracting 3n^2 from the sequence gives -7, -11, -15, -19, -23, -27, which has nth term -4n -3.
So the final answer will be 3n^2 -4n - 3.
Helpful 3What is the nth term of the quadratic sequence 4,7,12,19,28?
The first differences are 3, 5, 7, 9 and the second diffferences are all 2.
Since half of 2 is 1, then the first term of the quadratic nth term is n^2.
Next subtract n^2 from the sequence to give 3 for each term.
So the nth term will be n^2 + 3.
Helpful 3What is the nth term of 7,10,15,22,31,42?
The first differences are 3,5,7,9,11 and the second differences are 2.
The first term of the sequence is, therefore, n^2 (since half of 2 is 1).
Subtracting n^2 from the sequence gives 6.
So putting these 2 terms together gives a final answer of n^2 + 6.
Helpful 3Can you find the nth term of this sequence -3,0,5,12,21,32?
The first differences are 3,5,7,9,11, and the second differences are 2.
Therefore the first term in the quadratic sequence is n^2.
Subtracting n^2 from the sequence gives -4.
So the final answer of this sequence is n^2 -4.
(Just subtract 4 from your square number sequence).
Helpful 3Find the nth term of this sequence 9,12,17,24?
These numbers are 8 more than the square number sequence, so the nth term is n^2 + 8.
Helpful 3What is the nth term of this sequence of numbers 0,1,4,9,16?
This is your square number sequence starting at 0 instead of 1.
Therefore the nth term will be (n-1)^2.
Helpful 3Find the nth term of this sequence 8, 16, 26, 38, 52, 68, 86?
The first differences are 8, 10, 12, 14 , 16, 18, and the second differences are 2.
This means the first term of the sequence is n^2.
Subtracting n^2 from the sequence give 7, 12, 17, 22, 27, 32, 37, which has nth term 5n + 2.
So the final answer is n^2 + 5n + 2.
How would I find the nth term of this sequence 3,13, 27, 45, 67?
The first differences are 10, 14, 18, 22 and the second differences are 4. Therefore the first term is 2n^2 as half os 4 gives 2.
Subtracting 2n^2 from the sequence gives 1, 5, 9, 13, 17 which has nth term of 4n -3.
Putting all this together givers 2n^2 + 4n - 3.
Helpful 3What is the nth term of this fractional number sequence 1/2 , 4/3, 9/4, 16/5?
First look for the nth term of the numerators of each fraction (1,4,9,16). Since these are square numbers then the nth term of this sequence is n^2.
The denominators of each fraction are 2,3,4,5, and this is a linear sequence with nth term n + 1.
So putting these together the nth term of this fractional number sequence is n^2/(n+1).
Helpful 3What is the nth term of this: 4, 10, 18, 28, 40?
The first differences are 6,8,10,12, and the second differences are 2.
Since half of 2 is 1, then the first term of the nth term is n^2.
Subtracting n^2 from the sequence gives 3,6,9,12,15 which has a nth term of 3n.
So putting these together gives a nth term of the quadratic sequence of n^2 + 3n.
Helpful 3Find the nth term of this sequence 3,11,25,45?
The first differences are 8, 14, 20, and the second differences are 6.
Since half of 6 is 3, then the first term is 3n^2.
Subtracting 3n^2 leaves the sequence 0, -1, -2, -3 which has nth term -n + 1.
So the final answer is 3n^2 - n + 1.
Helpful 3What is the nth term for this sequence 6, 9, 14, 21, 30?
The fist differences are 3, 5, 7, 9, and the second difference are 2.
Since the second differences are 2, then the first term of the nth term is n^2 (Half 2).
Subtracting n^2 from the sequence gives 5.
So the final answer is n^2 + 5.
Helpful 2Find the nth term rule of this sequence 12,17,24,33,44,57,72?
The first differences are 5,7,9,11,13,15 and the second differences are 2.
Therefore the first term of the sequence is n^2.
Subtracting n^2 from the sequence gives 11, 13, 15, 17, 19, 21, 23 which has nth term 2n + 9.
So the formula is just n^2 + 2n + 9.
Helpful 2Can you find the nth term of this quadratic sequence. 3,11,25,45?
First, work out the first differences; these are 8, 14, 20.
Next, find the second differences, these are all 6.
So since half of 6 is 3, then the first term is 3n^2.
Subtracting 3n^2 from the sequence gives 0, -1, -2, -3 which has nth term of -n + 1.
So the nth term of this quadratic sequence is 3n^2 -n + 1.
Helpful 2Can you find the nth term of the sequence 3,11,25,45?
First differences are 8, 14, 20.
Second differences are 6, so the first term is 3n^2.
Minus 3n^2 from the sequence to give 0,-1-2,-3, which has nth term -n + 1.
So the final answer is 3n^2 -n + 1.
Helpful 2What are the first three terms for n^(2)+20?
To work this out the numbers 1,2 and 3 need to be substituted into the nth term.
So the first term is 1^2 + 20 = 21.
The second term is 2^2 + 20 = 24.
The third term is 3^2 + 20 = 29.
So the first three terms are 21,24,29.
Helpful 2Find the nth term of the sequence 1,11,27,49?
The first differences are 10, 16, 22, and the second difference are 6 meaning that the sequence is quadratic and the first term being 3n^2.
Subtracting 3n^2 from the sequence gives -2,-1,0,1 which has nth term n - 3.
So putting these terms together gives a final answer of 3n^2 + n - 3.
Helpful 2Find the nth term of this sequence 4, 7, 12, 19, 28?
These numbers are 3 more than the square number sequence, so the nth term is n^2 + 3.
Helpful 2Find the nth term of this sequence 4,16,36,64,100?
This sequence is 4 times bigger than the square number sequence, so the nth term is 4n^2.
Helpful 2How do I find the nth term of this sequence 0, 5, 12, 21, 32?
First differences are 5,7,9,11, and the second differences are 2.
The first term will, therefore, be n^2, as half of 2 is 1.
Subtracting n^2 from the sequence gives -1,1,3,5,7 which has nth term 2n - 3.
So the final nth term is n^2 + 2n - 3.
Helpful 2What is the nth term rule of the quadratic sequence 8,16,26,38,52,68,86?
The first differences of this sequence are 8, 10, 12, 14, 16 ,18, 22, and the second differences are 2.
Since half of 2 is 1 then the first term of the quadratic sequence is n^2.
Subtracting n^2 from the sequence gives 7, 12, 17, 22, 27, 32, 37 which has nth term 5n + 2.
So the final nth term is n^2 + 5n + 2.
Helpful 1What is the nth term of this quadratic number sequence 5, 9, 1, 29?
The first differences are 4, 8, 12, and the second differences are 4.
Since half of 4 is 2 then the first term of the nth term is 2n^2.
Subtracting 2n^2 from this sequence gives 3, 1, -1, -3 which has nth term of -2n + 5.
So putting this together gives 2n^2 -2n + 5.
Helpful 2What is the sequence formula for 6,17,34,57,86?
The first differences are 11, 17, 23, 29.
The second differences are 6.
Half of 6 is 3, so the first term of the sequence is 3n^2.
If you subtract 3n^2 from the sequence you get 3,5,7,9 which has the nth term of 2n + 1.
Therefore your final answer will be 3n^2 + 2n + 1.
Helpful 2What is the nth term of the sequence 3, 13, 27, 45?
The first differences are 10, 14, 18, and the second differences are all 4, so the sequence must be quadratic.
Half of 4 gives 2, so the first term of the nth term is 2n^2.
Subtracting 2n^2 from the sequence gives 1, 5, 9, 13 which has nth term of 4n -3.
So the final nth term is 2n^2 + 4n - 3.
Helpful 2Can you find the value of k of this sequence 1,-5,k,-23?
Assuming the sequence is quadratic then the first differences are -6, k + 5, and -23 - k.
The second differences are k + 11 and -2k and -28.
Since the second differences are the same of a quadratic sequence then k + 11 = -2k - 28.
This gives 3k = -39, and k = -13.
Helpful 2What is the nth term of this quadratic sequence 11,15, 23, 35?
The fist differences are 4, 8, 12, and the second difference are 4.
Since the second difference are 4, then the first term of the nth term is 2n^2 (Half 4).
Subtracting 2n^2 from the sequence gives 9, 7, 5, 3, which has nth term -2n + 11.
So the final answer is 2n^2 - 2n + 11.
Helpful 2Find the nth term of this number sequence 5,11,19,29?
The first differences are 6, 8, 10 and the second differences are 2.
Since half of 2 is 1, then the first term of the formula is n^2.
Subtracting n^2 from this sequence gives 4, 7, 10, 13 which has nth term 3n + 1.
So the final nth term formula is n^2 + 3n + 1.
What is the nth term rule of the quadratic sequence below? 4 , 15 , 30 , 49 , 72 , 99 , 130
The first differences of this sequence are 11, 15, 19, 23, 27 ,31 and the second differences are 4.
Since half of 4 is 2 then the first term of the quadratic sequence is 2n^2.
Subtracting 2n^2 from the sequence gives 2, 7, 12, 17, 22, 27, 32 which has nth term 5n - 3.
So the final nth term is 2n^2 + 5n - 3.
Helpful 1The first 5 numbers of a sequence are: 15, 25, 39, 57, 79. Whats the expression for Un?
The first differences are 10, 14, 18, 22, and the second differences are 4.
Since half of 4 is 2, then the first term is 2n^2.
Subtracting 2n^2 from the sequence gives 13, 17, 21, 25, 29 which has nth term of 4n + 9.
So the final answer is 2n^2 + 4n + 9.
Find the nth term of this sequence 8,18,33,53?
The first differnences are 10, 15, 20, and the second differences are 5.
This means the first term of the sequence is 2.5n^2.
Subtracting 2.5^n^2 from the sequence gives 5.5, 8, 10.5, 13, which has nth term 2.5n + 3.
So the nth term will be 2.5n^2 + 2.5n + 3.
Can you find nth term of this sequence 9, 15, 23, 33, 45?
The first differences are 6,8,10,12, and the second differences are 2.
Therefore the first term in the sequence is n^2 as half of is 1.
Subtracting n^2 from the sequence gives 8,11,14,17,20 which has nth term 3n + 5.
So the final answer is n^2 + 3n + 5.
Helpful 1Can you find the nth term of this sequence 2,14,36,68?
First find the first differences to give 12, 22, 32, and therefore the second differences are 10.
This means the first term will be 5n^2 as half of 10 is 5.
Subtracting 5n^2 from the sequence gives -3, -6, -9, -12, which has nth term -3n.
So the final formula for the sequence is 5n^2 - 3n.
Helpful 1What's the nth term of the sequence 1,3,9,19,33,51?
First differences are 2, 6,10,14,18.
Second differences are 4, so the first term is 2n^2.
Minus 2n^2 from the sequence to give, -1,-5-9,-13,17 which has nth term -4n + 3.
So the final answer is 2n^2 -4n + 3.
Helpful 1find the nth term of this quadratic sequence 4,7,12,19,28?
These numbers are 3 more than the square number sequence which is n^2.
So the final answer is n^2 + 3.
Helpful 1What is the nth term of the sequence 4 6 10 16 24 34 46?
The first differences are 2,4,6,8,10,12, and the second differences are 2.
So the first term of the sequence is n^2.
Subtracting n^2 from the sequence gives 3,2,1,0,-1,-2,-3 which has nth term -n + 4.
So the nth term is n^2 - n + 4.
Helpful 1Find the nth term of this sequence 4,7,12,19,28,39?
The first differences are 3, 5, 7, 9, 11 and the second differences are 2.
Half of 2 is 1, so the first term is n^2.
Subtract n^2 from the sequence gives 3.
So the nth term of the sequence is n^2 + 3.
Helpful 1What is the nth term rule of the quadratic sequence below? − 8 , − 8 , − 6 , − 2 , 4 , 12 , 22...?
The first differences are 0, 2, 4, 6, 8, 10.
The second differences are 2.
Half of 2 is 1, so the first term of the sequence is n^2.
If you subtract n^2 from the sequence gives -9, -12, -15, -18, -21, -24, -27 which has nth term -3n - 6.
Therefore your final answer will be n^2 -3n - 6.
Helpful 1Find the nth term of the sequence 1,7,17,31?
The first differences are 6, 10, 14.
The second differences are 4.
Half of 4 is 2, so the first term of the sequence is 2n^2.
If you subtract 2n^2 from the sequence you get -1 for each term.
Therefore your final answer will be 2n^2 - 1
Helpful 1What is the nth term rule of the quadratic sequence below? − 4 , − 3 , 0 , 5 , 12 , 21 , 32 , .
The first differences are 1, 3, 5, 7, 9, 11.
The second differences are 2.
Half of 2 is 1, so the first term of the sequence is n^2.
If you subtract n^2 from the sequence gives -5, -7, -9, -11, -13, -15, -17 which has nth term -2n - 3.
Therefore your final answer will be n^2 -2n - 3.
Helpful 1Find the nth term for this sequence : 4,7,12,19,28?
These terms in the sequence are 3 higher than the square number nth term, so the nth term is n^2 + 3
Helpful 1Can you find the nth term for this sequence:2 ,5 ,10,17,26,37?
These numbers are 1 more than the square number sequence so the answer will be n^2 + 1.
Can you find the nth term 11,14,19,26,35,46?
This sequence is 10 higher than the square number sequence, so the formula is nth term = n^2 + 10.
Helpful 1Find the nth term of this sequence -1 2 7 14 23?
These numbers are two smaller than the square number sequence (1,4,9,16,25...)
Since the nth term of the square numbers is n^2 then the formula for this sequence will be n^2-2.
Helpful 1What is the Nth term of 8, 16, 28 ,44?
First find the first differences to give 8, 12, 16, and therefore the second differences are 4.
This means the first term will be 2n^2 as half of 4 is 2.
Subtracting 2n^2 from the sequence gives 6, 8, 10, 12, which has nth term of 2n + 4.
So the final formula for the sequence is 2n^2 + 2n + 4.
Helpful 1Can you find the nth term of this sequence 1, 3, 7, 13, 21?
The first differences are 2,4,6,8, and the second differences are 2.
Therefore, the first term will be n^2.
Subtracting n^2 from the sequence gives 0,-1,-2,-3,-4 which has nth term of -n + 1.
So the final answer is n^2 - n + 1.
Helpful 1What is the nth term of this sequence -8,-2,8,22,40?
The fist differences are 6, 10, 14, 18 and the second difference are 4.
Since the second differences are 4, then the first term of the nth term is 2n^2 (Half 4).
Subtracting 2n^2 from the sequence gives -10.
So the final answer is 2n^2 - 10.
Helpful 1Find the nth term of this sequence: 6, 9, 14, 21, 30, 41?
These numbers are 5 more than square number sequence 1,4,9,16,25,36 ... which has nth term n^2.
So the final answer is n^2 + 5.
Helpful 1Find the nth term of this sequence 2,17,40,71?
First, work out the first differences; these are 15, 23, 31.
Next, find the second differences, these are all 8.
So since half of 8 is 4, then the first term is 4n^2.
Subtracting 4n^2 from the sequence gives -2, 1, 4, 7 which has nth term of 3n - 5.
So the nth term of this quadratic sequence is 4n^2 +3n - 5
Helpful 1Can you find the nth term of this sequence 1, 6, 15, 28, 45?
The first differences are 5, 9, 13, 17, and the second differences are 4.
Half of 4 is 2, so the first term is 2n^2.
Take this from the sequence to give -1, -2, -3, -4, -5 which has a nth term of -n.
So the final answer is 2n^2 - n.
Helpful 1Find the nth term of this sequence 9, 18, 31, 48, 69?
The first differences are 9, 13, 17, 21, and the second differences are all 4.
Since half of 4 is 2, then the first term of the sequence is 2n^2.
Now subtract 2n^2 from this sequence to give 7, 10, 13, 16, 19, which has nth term of 3n + 4.
So the final nth term is 2n^2 + 3n + 4.
Helpful 1What is the nth term rule if the quadratic sequence 4, 15, 30, 49, 72, 99, 130 ?
The first differences of this sequence are 11, 15, 19, 23, 27 ,31 and the second differences are 4.
Since half of 4 is 2 then the first term of the quadratic sequence is 2n^2.
Subtracting n^2 from the sequence gives 2, 7, 12,17, 22, 27, 32 which has nth term 5n - 3.
So the final nth term is 2n^2 + 5n - 3.
Helpful 1Can you find the nth term for this quadratic sequence 1,2,4,7,11?
The fist differences are 1, 2, 3, 4 and the second difference are 1.
Since the second differences are 1, then the first term of the nth term is 0.5n^2 (Half of 1).
Subtracting 0.5n^2 from the sequence gives 0.5,0,-0.5,-1,-1.5 which has nth term -0.5n + 1.
So the final answer is 0.5n^2 - 0.5n + 1.
Helpful 1Find nth term of this 0, 3, 8, 15, 24?
These numbers are 1 less than the square numbers, so the nth term is n^2 - 1.
Helpful 1What is the nth term of this quadratic number sequence 3,7,12,18?
The first differences are 4,5,6, and the second differences are 1, so the first term will be 0.5n^2.
Subtracting 0.5n^2 from the sequence gives 2.5,5,7.5,10 which has nth term of 2.5n.
So the final answer is 0.5n^2 + 2.5n.
Helpful 1Find the third term of 5n^2?
First work out 3^2 to give 9.
Then multiply 9 by 5 to give 45.
(You just need to do the squaring before the multiplying).
Helpful 1Find the nth term of this sequence -6,-3,2,9,18?
These numbers are 7 smaller than the square numbers so the nth term is n^2 - 7.
Helpful 1Can you find the nth term of this sequence -1, 5, 15, 29, 47?
The first differences are 6, 10, 14, 18, and the second differences are 4.
Half of 4 is 2, so the first term is 2n^2.
Take this from the sequence to gives -3 for each term.
So the final answer is 2n^2 - 3.
Helpful 1Find the nth term of this sequence -1,2,7,14,23?
These numbers are 2 less than the square number sequence 1,4,9,16,25....
Therefore the nth term will be n^2 - 2
Helpful 1Find the nth term of this sequence 3 9 19 33 51?
The first differences are 6, 10, 14, 18.
The second differences are 4.
Half of 4 is 2, so the first term of the sequence is 2n^2.
If you subtract 2n^2 from the sequence you get 1 for each term.
Therefore your final answer will be 2n^2 + 1.
Helpful 1Can you find the nth term of this sequence 4, 7, 12, 19, 28?
These numbers are 3 more than the square numbers 1, 4, 9, 16, 25, so the nth term is n^2 + 3.
Helpful 1How do I find the nth term of 4,7,12,19,28?
These numbers are 3 more than the square number sequence 1,4,9,16,25.
So if the square number sequence has nth term n^2 then this sequence is n^2 + 3.
Find the Nth term rule of 7,15,25,37,51?
The first differences are 8, 10, 12, 14 and the second differences are 2.
Since half of 2 is 1 then the first term is n^2.
Subtracting n^2 from the sequence gives 6, 11, 16, 21, 21 which has nth term 5n + 1.
So putting this together gives n^2 + 5n + 1.
5th term for 3,6,10?
The first differences are 3 and 4.
So to get the 4th term add on 5 to 10 to give 15.
And to get the 5th term add on 6 to 15 to give 21.
What is the nth term of 4,7,12,19,28?
These are 3 more than the square number sequence so the answer is n^2 + 3.
What is the nth term rule of the quadratic sequence below? − 7 , − 6 , − 3 , 2 , 9 , 18 , 29 , . . .
The first differences of this sequence are 1, 3, 5, 7, 9 ,11 and the second differences are 2.
Since half of 2 is 1 then the first term of the quadratic sequence is n^2.
Subtracting n^2 from the sequence gives -8, -10, -12, -14, -16, -18 which has nth term -2n - 6.
So the final nth term is n^2 - 2n - 6.
Can you find the nth term rule of this pattern 8, 14, 22, 32, 44, 58, 74?
The first differences are 6, 8, 10, 12, 14, 16 and the second difference are 2.
Half of 2 is 1, so the first term is n^2.
Subtract n^2 from the sequence gives 7, 10, 13, 16, 19, 22, 25 which has nth term 3n + 4.
So the nth term of the sequence is n^2 + 3n + 4.
How do you find nth term of this quadratic sequence 3,6,11,18,27,38?
The numbers in the sequence are 2 higher than the the square number sequence of 1,4,9,16,25,36.
Therefore the nth term is n^2 + 2.
Find the nth term of this sequence -2,1,6,13,22,33?
The numbers in this quadratic sequence are 3 smaller than the square number sequence, so the nth term is n^2 - 3.
What is the nth term rule of the quadratic sequence below? 7,14,23,34,47,62,79
The first differences are 7,9,11,13,15,17,19,21 and the second difference are 2.
Half of 2 is 1, so the first term is n^2.
Subtract n^2 from the sequence gives 6, 10, 14, 18, 22, 26, 30 which has nth term 4n + 2.
So the nth term of the sequence is n^2 + 4n + 2.
what is the nth term of:4,9,16,25,36 ?
The first differences are 5, 7, 9, 11.
The second differences are 2.
Half of 2 is 1, so the first term of the sequence is n^2.
If you subtract n^2 from the sequence you get 3,5,7,9,11 which has the nth term of 2n + 1.
Therefore your final answer will be n^2 + 2n + 1.
What is the nth term of this sequence 1,5,11,19?
The first differences are 4, 6, 8, and the second differences are 2.
This means the first term is n^2.
Subtracting n^2 from this sequence gives 0, 1, 2, 3, which has nth term n - 1.
So the final answer is n^2 + n - 1.
What's the nth term of 3,11, 25, 45?
The first differences are 8, 14, 20, and the second differences are 6.
This means the first term is 3n^2.
Subtracting 3n^2 from this sequence gives 0, -1, -2, -3, -4 which has nth term -n + 1.
So the final answer is 3n^2 -n + 1.
Find the nth term of this sequence -5,-2,3,10,19?
These numbers are 6 smaller than the square number sequence (1,4,9,16,25...)
Therefore the nth term is n^2 - 6.
Find the nth term of this sequence? -5,-4,-1,4,11,20,31
The first differences are 1, 3, 5, 7, 9, 11 and the second differences are 2.
Therefore the first term is n^2.
Subtracting n^2 from the sequence gives -6, -8, -10, -12, -14, -16, -18 which has nth term -2n - 4.
Therefore the nth term of the sequence is n^2 - 2n - 4.
Write an expression in terms of n for 19,15,11?
This sequence is linear and not quadratic.
The sequence is going down by 4 each times so the nth term will be -4n + 23.
Find the nth term of this quadratic sequence 6,12,20,30,42,56,72?
The first differences are 6,8,10,12,14,16, and the second differences are 2.
Therefore the first term is n^2 (as half of 2 is 1).
Subtracting n^2 from the sequence gives 5, 8, 11,14,17,20,23 which has nth term of 3n + 2.
So the final nth term is n^2 + 3n + 2.
What is the nth term rule of the quadratic sequence below? − 5 , − 4 , − 1 , 4 , 11 , 20 , 31 ,
The first differences are 1, 3, 5, 7, 9, 11, and the second differences are 2.
This means the first term is n^2.
Subtracting n^2 from this sequence gives -6, -8, -10, -12, -14, -16, -18 which has nth term -2n - 4.
So the final answer is n^2 - 2n - 4.
Find the nth term of this sequence 6, 10, 18, 30?
The first differences are 4, 8, 12, and so the second differences are all 4.
Halving 4 gives 2, so the first term of the sequence is 2n^2.
Subtracting 2n^2 from the sequences gives 4,2,0,-2, which has the nth term -2n + 6.
Therefore, the formula for this sequence is 2n^2 - 2n + 6.
Find the nth term of this sequence− 7 , − 6 , − 3 , 2 , 9 , 18 , 29?
The first differences are 1, 3, 5, 7, 9, 11, and the second differences are 2.
Since half of 2 is 1, then the first term is n^2.
Subtracting n^2 leaves the sequence -8, -10, -12, -14, -16, -18, -20 which has nth term -2n - 6.
So the final answer is n^2 - 2n - 6.
What is the first 5 terms if nth term is 2n^2-29?
Start with the square numbers 1,4,9,16,32.
Multiply them by 2 to give 2,8,18,32,50.
Now subtract 29 to give -27, -21, -11, 3, 21.
What is the nth term of 6,12,20,30,42,56,72?
The first differences are 6, 8, 10, 12, 14, 16, and the second differences are all 2.
Since half of 2 is 1, then the first term of the sequence is n^2.
Now subtract n^2 from this sequence to give 5, 8, 11, 14, 17, which has nth term of 3n + 2.
So the final nth term is n^2 + 3n + 2.
On some practice questions I have done, the differences supposed to give me b and c give me the same number every time (e.g. 4, 4, 4, 4)~ does that mean b is 0?
Yes thats correct, b = 0. So you just have the first term and a constant for the second term.
Find the nth term of this sequence 8,23,48,83,128?
The first differences are 15, 25, 35, and the second differences are 10.
Since half of 10 is 5 then the first term is 5n^2.
Subtracting 5n^2 from the sequence gives 3 for each term.
Therefore the nth term is 5n^2 + 3.
What is the nth term for this quadratic sequence 11,14,19,26,35,46?
The numbers in the sequence are 10 more than the square number sequence 1,4,9,16,25 which has nth term n^2.
So the final answer is n^2 + 10.
Find the nth term of this sequence 1,2,3,4,5?
This sequence is not quadratic, as the first differences are all the same.
This means the sequence is an increasing linear sequence which has nth term of n.
What is the nth term rule of the quadratic sequence below? − 4 , − 3 , 0 , 5 , 12 , 21 , 32 ...
The first differences are 1, 3, 5, 7, 9, 11 and the second differences are 2.
Since half of 2 is 1, then the first term will be n^2.
Subtracting n^2 from the sequence is -5, -7, -9, -11, -13, -15, -17 which has nth term of -2n - 3.
Therefore the overall formula will be n^2 -2n - 3.
Find the nth term of this sequence 1,6,15,28?
The first differences are 5, 9, 13 and the second differences are 4.
Since half of 4 is 2, then the first term of the formula is 2n^2.
Subtracting 2n^2 from this sequence gives -1, -2, -3, -4 which has nth term -n
So the final nth term formula is 2n^2 -n.
Can you find the nth term of 4,7,12..?
These numbers are three more than the square number sequence 1,4,9, so the nth term will be n^2 + 3.
What is the nth term of 4, 8,15, 25, 38?
The first differences are 4, 7, 10, 13, and the second differences are 3.
Since half of 3 is 1.5, then the first term will be 1.5n^2.
Subtracting 1.5n^2 from the sequence gives 2.5, 2, 1.5, 1 which has nth term -0.5n + 3.
Therefore the final answer is 1.5n^2 -0.5n + 3.
If the nth term is 3(n+1) what is the sequencs?
First multiply out the bracket to give 3n + 3.
Now substitute n = 1 to 5 into the sequence to give 6,9,12,15,18 and so on.
Find the nth term of this quadratic sequence 2 7 14 23 34 47?
The first differences are 5, 7, 9, 11, 13, and the second differences are 2.
Half of 2 is 1, so the first term is n^2.
Subtracting n^2 gives 1, 3, 5, 7, 9, 11 which has nth term 2n - 1.
Therefore the nth term is n^2 + 2n - 1.
Find nth term of this sequence 4,10,18,28,40?
The first differences are 6, 8,10,14 and the second differences are 2.
Half of 2 is 1, so the first term of the formula is n^2.
Subtracting n^2 from the sequence gives 3,6,9,12,15 which has nth term 3n.
Therefore, the final nth term is n^2 + 3n.
Find the nth term for this sequence -5,-2,3,10,19?
The numbers in this sequence are 6 less than the square numbers 1, 4, 9, 16, 25.
Therefore the nth term is n^2 - 6.
Find the nth term of this sequence 9,19, 33, 51, 73, 99?
The first differences are 10, 14, 18, 22, 26 and the second differences are 4 meaning the first term is 2n^2.
Subtracting 2n^2 from the sequence gives 7, 11, 15, 19, 23 which has nth term 4n + 3.
So the final answer is 2n^2 + 4n + 3.
Find the nth term of this sequence 9,23,43,69,101,139?
The first differences are 14, 20, 26, 32, 38 and the second differences are 6, meaning that the first term is 3n^2.
Subtracting 3n^2 from the sequence gives 6, 11, 16, 21, 26, 31 which has nth term 5n + 1.
So the final answer is 3n^2 + 5n + 1.
What is the nth term formula for the sequence which begins 87, 74, 61, 48?
This sequence is linear and not quadratic.
The first differences are -13, so compare the sequence with -13, -26,- 39, -52.
This will give a final answer of -13n + 100.
What is the function rule of 3,6,11,18,... sequence?
These numbers are two more than the square square number sequence 1,4,9,16, which has nth term n^2.
So the nth term for this sequence is n^2 + 2.
Find the sequence from 2n^2-1?
First start with n^2 which is 1,4,9,16,25...
Now multiply these numbers by 2 to give 2,8,18,32,50...
Finally subtract 1 from these numbers to give 1,7,17,31,49...
Find the nth term of this sequence 4,9,14,19?
This sequence is linear not quadratic as the first differences are the same.
It has nth term 5n -1.
Could you please find the nth term of this sequence 3, 9, 17, 27, and 39?
The first differences are 6, 8, 10, 12.
The second differences are 2.
Half of 2 is 1, so the first term of the sequence is n^2.
If you subtract n^2 from the sequence you get 2,5,8,11,14 which has the nth term of 3n - 1
Therefore your final answer will be n^2 + 3n - 1
Find the nth term of the sequence 302,600,894,1184?
The first differences are 298, 294, 290.
The second differences are -4.
Half of -4 is 2, so the first term of the sequence is -2n^2.
If you subtract n^2 from the sequence gives 304, 608, 912, 1216 which has nth term 304n.
Therefore your final answer will be -2n^2 + 304n.
Find the nth term of this sequence 5,5,3,-1,-7?
The first differences are 0, -2, -4, -6, and the second differences are all 2.
Half of -2 is -1 so the first term is -n^2.
Subtracting -n^2 from the sequence gives 6, 9, 12, 15, 18 which has nth term 3n + 3.
So the final nth term of this quadratic sequecne is -n^2 + 3n + 3.
Find the nth term of this sequence 8,14, 22, 32, 44, 58, 74?
The first differences are 6,8,10,12,14,16, and the second differences are 2.
Half of 2 is 1, so the first term is n^2.
Subtracting n^2 from the sequence is 7, 10, 13, 16, 19, 22, 25 which has nth term 3n +4.
So the final answer is n^2 + 3n + 4.
The nth term for 10, 13, 18, 25?
These numbers are 9 more than the square numbers, so the nth term is n^2 + 9.
What is the quadratic nth term of 6, 15, 30, 51?
The first differences are 9, 15, 21, and the second differences are 6.
Since half of 6 is 3, then the first term will be 3n^2.
Subtracting 3n^2 from the sequence gives 3 for each term.
Therefore the final answer is 3n^2 + 3.
Find the expression of this sequence? -5,-2,5,16,31
The first differences are 3,7,11,15, and the second differences are 4.
Therefore the first term of the sequence is 2n^2.
Subtracting 2n^2 from the sequence gives -7, -10, -13, -16, -19 which has nth term -3n - 4.
So the formula is 2n^2 -3n - 4.
What is the ninth term of this sequence? 2,11,26,47,74,107?
First work out the nth term.
The first differences are 9,15,21,27,33, and the second differences are 6.
Therefore the first term of the sequence is 3n^2.
Subtracting 3n^2 from the sequence gives -1.
So the formula is 3n^2 - 1.
Now substitute n = 9 into this formula, 3 multiplied by 9^2 - 1 gives 242.
What is the nth term of this sequence: 3,18,41,72,111?
The first differences are 15,23,31,39, and the second differences are 8
Therefore the first term of the sequence is 4n^2.
Subtracting 4n^2 from the sequence gives -1, 2, 5, 8, 11 which has nth term 3n - 4.
So the formula is just 4n^2 + 3n - 4.
Find the nth term of this sequence 1,3,7,13,21?
First, work out the first differences; these are 2, 4, 6,8.
Next, find the second differences, these are all 2.
So since half of 2 is 1, then the first term is n^2.
Subtracting n^2 from the sequence gives 0, -1, -2, -3, -5 which has nth term of -n + 1.
So the nth term of this quadratic sequence is n^2 -n + 1.
Find the nth term of this sequence -4, -3,0 , 5 , 12 , 21 ,32?
The first differences are 1, 3, 5, 7, 9, 11.
The second differences are 2.
Half of 2 is 1, so the first term of the sequence is n^2.
If you subtract n^2 from the sequence you get -5,-7, -9 , -11, -13. -15, -17 which has the nth term of -2n -3.
Therefore your final answer will be n^2 - 2n - 3.
Find the sequence for n^2-3n+2?
First sub in n = 1 to give 0.
Next sub in n =2 to give 0.
Next sub in n = 3 to give 2.
Next sub in n = 4 to give 6.
Next sub in n = 5 to give 12.
Keep going to find other terms in the sequence.
What are the first 4 term of n squared +3?
Sub in n=1, 1^2 + 3 = 4.
Next sub in n=2, 2^2 + 3 = 7.
Next sub in n = 3, 3^2 + 3 = 12.
Next sub in n = 4, 4^2 + 3 = 19.
So the first 4 terms are 4,7,12,19.
What is the nth term rule of the quadratic sequence below? − 5, − 4, − 1, 4, 11, 20, 31, . . .
The first differences are 1, 3, 5, 7, 9, 11, and the second differences are 2.
Half of 2 is 1 so the first term is n^2.
Take this from the sequence to give -6, -8, -10, -12, -14, -16, -18 which has nth term of -2n - 4.
So the final answer is n^2 - 2n - 4.
What is the nth term of this sequence -5, -4, -1, 4, 11, 20, 31?
The first differences are 1, 3, 5, 7, 9, 11 and the second differences are 2.
Half of 2 is 1, so the first term is n^2.
Take this from the sequence to give -6, -8, -10, -12, -14, -16, -18 which has nth term of -2n-4.
So the final answer is 2n^2 - 2n - 4.
Find the nth term for this sequence 4, 9, 16, 25, 36?
(n+1)^2
Find the nth erm of this sequence 10,22,40,64,94,130?
The first differences are 12, 18, 24, 30, 36, and the second differences are 6.
This means the first term is 3n^2 (half of 6).
Subtracting 3n^2 from the sequence gives 7, 10, 13, 16, 19, 22 which has nth term 3n + 4.
So the nth term of this quadratic is 3n^2 + 3n + 4.
Find the nth term for -2,4,14,28?
The first differences of this sequence are 6, 10, 14, and the second differences are 4.
Since half of 4 is 2, then the first term of the quadratic sequence is 2n^2.
Subtracting 2n^2 from the sequence gives -4.
So the final nth term is 2n^2 - 4.
What is second and fifth term of the sequence 3n^2-1?
Substitute n = 2 to work out the second term, so 2^2 is 4, 4 times 3 is 12, and subtract 1 is 11.
Substitute n = 5 to work out the fifth term, so 5^2 is 25, 3 times 25 is 75, and subtract 1 is 74.
Can you find the nth term of 3, 10, 21, 36, 55?
First differences are 7, 11, 15, 19.
Second differences are 4.
The first term is therefore 2n^2 (Since half of 4 is 2).
Subtracting 2n^2 from the sequence gives 1, 2, 3, 4, 5, which has nth term n.
So the final answer is 2n^2 + n.
How do I find the nth term of the quadratic sequence -1, 2, 7, 14, 23?
These numbers are two less than the square numbers, so the nth term is n^2 - 2.
Find the nth term of this sequence 8,14,22,32,44,58,74?
First differences are 6, 8, 10, 12, 14, 16.
Second differences are 2.
First term is therefore n^2 (Since half of 2 is 1)
Subtracing n^2 from the sequence gives 7, 10, 13, 16, 19, 22, 25 which has nth term 3n + 4.
So the final answer is n^2 + 3n + 4.
How do you find the second term of this sequence 3, x, 29, 51?
The first differences are x - 3, 29 - x, and 21. The second differences are 32 - 2x and -8 + x.
Since the second differences are the same then 32 - 2x = -8 + x.
So 3x = 40, and x = 40/3 or 13 1/3.
Can you find the nth term of -7, -6, -3, 2, 9, 18, 29?
First differences are 1, 3, 5, 7,9, 11.
Second differences are 2.
First term is therefore n^2 (Since half of 2 is 1)
Subtracing n^2 from the sequence gives -8, -10, -12, -14, -16, -18, -20 which has nth term -2n - 6.
So the final answer is n^2 - 2n - 6.
Can you find the nth term of this sequence: 12,17,24,33,44,57,72?
First differences are 5,7,9,11,13,15
Second differences are 2, so the first term is n^2.
Minus n^2 from the sequence to give, 11,13,15,17,19,21,23 which has nth term 2n + 9.
So the final answer is n^2 + 2n + 9.
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Comments
hellom8
6 months ago
this is very helpful , cheers
confusedchild
11 months ago
im still a bit confused how you work out 'c' like how did you get -10 / 0?
louisearabiana
14 months ago
where does this difference came from, like the 4,8,12,16,20?
- AUTHOR
Mark
21 months ago from England, UK
This would rarely happen, but you can still apply the same method. Just put a decimal before n squared.
its ya boi
21 months ago
What if the second difference is an odd number?
Silver49
5 years ago
Very good explanation I will recommend this site to any one who has got problem understanding quadratic sequence
MKING
5 years ago
its it the same if you get for example 3n+3n+3n+1 like 3 nth terms do u just go and make a third sequence from your second sequence
cool guy
6 years ago
what do you do if the number only repeats after 4 differences:
1 1 2 7 21
0 1 5 14 1
1 4 9 2
3 5 3
2 4
What is the equation?
Gervasius Stephanus
6 years ago
Conceptual undertanding is very important for students to comprehend quadratic sequence. Hence, the logic of determining the terms of a given sequence defined by a quadratic formula should be the starting point.
Dr Gervasius Stephen
6 years ago
The procedure helps far better but understanding of the concept per se in changing the sequence to arithmetic number sequence should be greatly emphasised.
MathFabPhobiaCured
6 years ago
dat is just dam cul. luving dis site. helpd me a lot.
quad eqns made easy for us math phobs people.
shafster
6 years ago
its epic
sid
7 years ago
brilliant i was having trouble with quadratic sequences and this helped a lot thanks
Angel
7 years ago
N is number of term.
Angel
7 years ago
Dats cul
matthias caruana
7 years ago
In step one there's a mistake in the first difference
it should be 11,15,19,23
Me.
8 years ago
thanks for this, had trouble understanding for my maths homework
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