If 9th term of an a.p. is zero then proof that 29th term is double the

1.	If 9th term of an a.p. is zero then proof that 29th term is double the 19th term
Answer» Too.long process.. you have done<br>Let a and b respectively be the first term and common difference of the AP Given A9=0So ,a+(9-1)d=0a+8d=0a=-8dNow ,29 th term= a+28d=-8d+28d=20d=210d=2(-8d+18d)=2(a+18d)=219th term Thus ,the 29 th term of the AP is double the 19th term

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