1. sum of (n/2^n) from n=1 to infinite 2. sum of (n(n-1)x^n) from n=2 to infinite
Follow Math Help Forum on Facebook and Google+
Hello, Jojo123! Here's the first one . . . We are given: . Multiply by The geometric series has a sum of . . So we have: .
Originally Posted by Jojo123 2. sum of (n(n-1)x^n) from n=2 to infinite (assuming |x|<1) hence
Originally Posted by Jojo123 2. sum of (n(n-1)x^n) from n=2 to infinite Put From here it's not hard to see that Now put and compute
View Tag Cloud