Question

Find the nth term of this quadratic sequence. 4 ,11, 22,37,30,47

Answer 1

Question:

Find the nth term of this sequence 4,7,12,19,28?

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Answer:

First, work out the first differences; these are 3, 5, 7, 9.

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 3.

So the nth term of this quadratic sequence is n^2 + 3.

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Answer 2

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First, work out the first differences; these are 3, 5, 7, 9.

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 3.

So the nth term of this quadratic sequence is n^2 + 3.

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