If fourth term of an A. P. is zero, show that its 25th term is thrice its 11th term.? ( A.P. = arithmetic progression )

Proof

1 Answer
Feb 19, 2016

(see below)

Explanation:

For an arithmetic progression with a difference of d between terms and an initial value of a0:
XXXak=a0+kd

We are told that a4=a0+4d=0

a11=a0+11d
XXX=a0+4d+7d
XXX=a4+7d
XXX=7d

a25=a0+25d
XXX=a0+4d+21d
XXX=a4+21d
XXX=21d

a25=3×a11