Question

the 24th term of an ap is twice its 10th term .show that it's 72 term is 4 times its 15 term

Answer 1

a,±23d=2(a±9d)
a±23d=2a±18d
on solving we get
a=5d....... (1)
to proove:_
a±71d=4(a±14d)
on putting the value of (1) in
a±71d =4(a±9d)
we get
76d=76d