Question

Can 2n² – 7 be the n^th term of an A.P.? Explain.

Answer 1

We have 2n² – 7,

Substitute n = 1, 2, 3, …, we get

2(1)² – 7, 2(2)² – 7, 2(3)² – 7, 2(4)² – 7, ….

–5, 1, 11, ….

Difference between the first and second term = 1 – (–5) = 6

And difference between the second and third term = 11 – 1 = 10

Here, the common difference is not same.

Therefore, the n^th term of an A.P. can't be 2n² – 7.