Question

If 5 times of the 5th term of ap is equal to 8 time of the 8th term. Prove that its 13th term is 0

Answer 1

Let of the AP

First term= a

Common difference=d

ATQ

5[a+(5-1)d]=8[a+(8-1)d]
5(a+4d)=8(a+7d)
5a + 20d = 8a + 56d
3a = 36d
a= -12d

Now 13th term
a+(13-1)d
=-12d+12d
=0
(proved)

Answer 2

Hii There!!!
See the above attachment....