Question

If 9th term of an AP is zero , prove that it's 29th term is double of it's 19th term.

Answer 1

Given,
T9=0
To prove,
T29=2*T19
ATQ,
a+8d=0
a=-8d
Now,
T19=a+18d
=-8d+18d
=10d
T29=a+28d
=-8d+28d
=20d
Clearly,
2*10d=20d
2*T19=T29

Hope this helps you!

Answer 2

Hence Proved....!!!!