Question

Following are APs or not? If they form an A.P. find the common difference d and write three more terms: 

-10, -6, -2, 2 …

Answer 1

−10, −6, −2, 2 …

It can be observed that

a₂ − a₁ = (−6) − (−10) = 4

a₃ − a₂ = (−2) − (−6) = 4

a₄ − a₃ = (2) − (−2) = 4

i.e., a_k+1 − a_k is same every time. Therefore, d = 4

The given numbers are in A.P.

Three more terms are

a₅ = 2 + 4 = 6

a₆ = 6 + 4 = 10

a₇ = 10 + 4 = 14