Question
Sun March 13, 2011 By: Nivedita Rao
 

if the 9th term of an AP is 0,prove that its 29th term is twice its 19th term.

Expert Reply
Sun March 13, 2011
dear student,
to find any term of the A.P. we need its first term a and common diff d right?
so our aim should be to find a and d or the relation between a and d using the given info.
ATQ,
9th term of the A P is zero.
a+8d=0
so a =-8d...(i)
now 29th term is=a+28d=-8d+28d=20d...using (i)
and
19th term = a+18d=-8d+18d=10d
so we see that
29th term =2 x (19th term)
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