Question

The first term of an A.P. is -2 and the 10th term is 16. Determine the 15th term.

Answer 1

Step-by-step explanation:

Let a be the first term and d be the common difference of the AP.

Genereal term of an A.P.⇒a

n

=a+(n−1)d

We have, a

8

=31 and a

15

=16+a

11

⟹a+7d=31 and a+14d=16+a+10d

⟹a+7d=31 and 4d=16

⟹a+7d=31 and d=4⟹a+7×4=31

⟹a+28=31⟹a=3

Hence, the AP is a,a+d,a+2d,a+3d ...

i.e.,3, 7, 11, 15, 19, ...