Question

sum_{n=2}^{infty} [2/(n^2-1)] with steps

Answer 1

\[\sum_{n=2}^{\infty} [2/(n^2-1)]\]

Answer 2

rewrite as
\[\frac{2}{n^2-1}=\frac{1}{n-1}-\frac{1}{n+1}\] the see that you have a telescoping sum of which only the first two terms survive

Answer 3

adding up leaves
\[1+\frac{1}{2}=\frac{3}{2}\]