Question

Please help with the following factorial example:

Answer 1

how do i get from the middle term to the last term....not seeing what happened

Answer 2

Okay i'll just give the answer:\[\frac{(2n+2)!n!}{2n!(n+1)!}=\frac{(2n+2)(2n+1)!n!}{2n!(n+1)n!}=\frac{(2n+2)(2n+1)(2n)!n!}{2n!(n+1)n!}\]