Question

The sum of the third and the seventh terms of an ap is 6 and their product is 8 find the sum of the first 16 terms of the ap

Answer 1

According to the question,
a+2d+a+6d=6( given)
a+4d=3
a=3-4d.....equ 1
Now,
( a+2d)(a+6d)=8 (given)
a^2+8ad+12d^2=8
Putting value of a , we get:
d=7.7
Putting value of d in equ 1 we get,
a=-27.8
Thus the 16 th term of an AP = a+15d
=143.3

Hope it helps you......