in Quantitative Aptitude edited by
129 views
0 votes
0 votes

Let $S=2x + 5x^2 + 9x^3 + 14x^4 + 20x^5 \dots \dots $ infinity. The coefficient of $n$-th term is$\frac{n(n+3)}{2}$. Then the sum $S$ is

  1. $\frac{x(2-x)}{(1-x)^3}$
  2. $\frac{(2-x)}{(1-x)^3}$
  3. $\frac{x(2-x)}{(1-x)^2}$
  4. None of these
in Quantitative Aptitude edited by
13.4k points
129 views

Please log in or register to answer this question.

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true