Question

In an AP if the common difference (d) = - 4, and the seventh term (a₇) is 4, then find the first term.

Answer 1

Given d = – 4 and a₇ = 4 

We know that nth term of AP is 

a_n = a + (n – 1)d 

a₇ = a + (7 – 1)d    [n = 7] 

4 = a + 6(– 4) 

a = 4 + 24 = 28

First term of an AP = 28