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
Alan P.
Feb 19, 2016

(see below)

Explanation:

For an arithmetic progression with a difference of d between terms and an initial value of a_0:
color(white)("XXX")a_k=a_0+k*d

We are told that a_4=a_0+4d=0

a_11=a_0+11d
color(white)("XXX")=a_0+4d+7d
color(white)("XXX")=a_4+7d
color(white)("XXX")=7d

a_25=a_0+25d
color(white)("XXX")=a_0+4d+21d
color(white)("XXX")=a_4+21d
color(white)("XXX")=21d

a_25=3xxa_11

Related questions
Impact of this question
1408 views around the world
You can reuse this answer
Creative Commons License