Question

In an AP, if the common difference (d) = -4 and the seventh term $\left(a_7\right)$ is 4, then find the first term.

Answer 1

Given,
d = -4
$a_7=4$
$a_n=a+(n-1)d$
a + 6d = 4
a + 6(-4) = 4
a - 24 = 4
a= 4 + 24
a = 28