Question

Which of the following are APs? If they form an A.P. find the common difference d and write three more terms. -1.2, -3.2, -5.2, -7.2 …

Answer 1

−1.2, −3.2, −5.2, −7.2 …

It can be observed that

a₂ − a₁ = (−3.2) − (−1.2) = −2

a₃ − a₂ = (−5.2) − (−3.2) = −2

a₄ − a₃ = (−7.2) − (−5.2) = −2

i.e., a_k+1− a_k is same every time. Therefore, d = −2

The given numbers are in A.P.

Three more terms are

a₅ = − 7.2 − 2 = −9.2

a₆ = − 9.2 − 2 = −11.2

a₇ = − 11.2 − 2 = −13.2