I got a question which is about limit, after thinking still don't know how to starts it.
Qrove that (n+a)!/(n+b)! ~ n^(a-b) as n goes to +ive infinite (for fixed a,b>0)
and the Qs provide some formula to use
Euler's limit: '[1+(x/n)]^n' → 'e^x' as n goes to infinite
Stirling's formula: n! ~ [root(2πn)](n/e)^n
Thanks very much.