Question

How to find the nth term of an A.P -15, -18, -21

Answer 1

Answer:

given,

A1=-15

A2=-18

A3=-21

to find nth term

we should find common difference(d).

d=A2-A1

=-18-(-15)

=-18+15

=-3

d=-3

An=A+(n-1)d

An=-15+(n-1)-3

An=-15-3n+3

An=-12-3n

12=-3n

n=12/-3

n=-4