Question

Can someone explain to me how this is true? Very simple differential.

Answer 1

\[\frac{ 1 }{(1-x)^{2} }=\frac{ d }{ dx }\frac{ 1 }{ 1-x }=\frac{ d }{ dx }\sum_{n=0}^{\infty}x^{n}=\sum_{n=0}^{\infty}(n+1)x^{n}\]

Answer 2

What is the problem?