Question

Which term of the ap 21 18 15 . . . is – 81? also is any term is 0? give reason for your answer?

Answer 1

a=21
d=18-21=(-3)

-81=21+(n-1)(-3)
-81-21/-3=n-1
34=n-1
n=35

if an is 0
0=21+(n-1)(-3)
-21/-3=n-1
n=8

Answer 2

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