Question

Tf the 5 times the 5th term of AP is
equal to 8 term, show that it it's
18th term is zero.​

Answer 1

Answer:

Step-by-step explanation:

We know that ,

an=a+(n-1)d

5*a5=8*a8

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

5a+20d=8a+56d

0=56d-20d+8a-5a

0=36d+3a

Taking 3 common,

a+12d=0

a13=0

Hence proved.