Question

For an given AP, Five times the 5th term equals eight time the 8th term.Find the 13th term of an AP​

Answer 1

General term of AP=a+(n-1)d

5th term=a+(5-1)d=a+4d

8th term=a+(8-1)d=a+7d

A.T.Q.

5(a+4d)=8(a+7d)

5a+20d=8a+56d

5a-8a=56d-20d

-3a=36d

a= -36/3

a= -12d

13th term=a+(13-1)d

= -12d+12d

=1

Therefore, Thirteenth term of the given AP is 1