1. The problem statement, all variables and given/known data equation: http://img292.imageshack.us/img292/6239/untitledkl6.jpg 2. Relevant equations can use geometric series i think. 3. The attempt at a solution I think this is a geometric series, i plugged numbers into the equation, starting from 1 and got: 1/16 + 64/7 + 256/49 +... maybe i can use a formula something like this? --> 1/(1-a) need help with this please.