Question

If
a = 1 ,r= -2 find t4​

Answer 1

$a = 1 \\ d = - 2 \\ n = 4 \\ a4 =$

$an = a + d(n - 1) \\ a4 = a + 3d \\ = 1 + 3( - 2) \\ = 1 - 6 \\ = - 5$

Hope it helps.

Thanks.