Question

if the 9th term of AP is zero then prove that its 29th term is twice its 19th terms

Answer 1

hello

let 1st term = a
and common difference=d

so a+8d=0 _______(1)

and

29th term = a+28d = -8d+28d=20d (from 1)

and 19th term= -8d +18d =10d

so 29th term = 20d =2×10d = 2×(19th term)


hence proved

thanks