Question

If the 3rdand the 9th terms of an AP are 4 and -8 respectively,which term of this AP is zero?​

Answer 1

Common difference = -2

$1^{st}$ term = $3^{rd}$ - 2d

            = 4-(-4)

            = 8

$n^{th}$term = dn+(f-d)

            = -2n+10

-2n+10 = 0

-2n = -10

n = 5

$5^{th}$ term = 0

HOPE IT HELPS U.........................