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

Asked by nivi95 | 13th Mar, 2011, 03:24: AM

Expert Answer:

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)

Answered by  | 13th Mar, 2011, 10:39: AM

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