Question

The sum of 5th and 9th term of an AP is 30. If its 25th term is 3 times its 18th term ,then find its AP.

Answer 1

3rd term is a+2d

9th term is a+8d

so, a+2d=4 …(i)

a+8d=-8 ….(ii)

On subtracting equ (i) & (ii) we get,

-6d=12

i.e, d=-2