Re: gokhale:sec B q5.

Posted by Chinni18 on Jun 08, 2012; 9:50am
URL: http://discussion-forum.276.s1.nabble.com/gokhale-sec-B-q5-tp7577435p7577572.html

The second series is
7[ 1/3 + 1/(3^2) +1/(3^3) +........] -4[ 1/2 +(1/2^2) + 1/(2^3) + ..........]
Using the formula for sum to infinity of  a GP
7 [(1/3)/{1-(1/3)} -4[(1/2) / {1-(1/2)}]
=7(1/2) - 4(1)
=7/2 - 4
= -1/2