Question

Please solve 5 th question quickly

Answer 1

a3=4

or a+2d=4 _______(1)

a19=-8

or a+18d=-8. _______(2)

on subtracting eq (1) from (2),we get

16d=-12

d=-3/4

putting d=-3/4 in eq(2),we get

a=9/2

Now,

let nth term of ap is 0.

so, a+(n-1)d=0

9/2-3n/4+3/4=0

3n=21

n=7