Question

E6, vă rog. 65p vă dau, hai vă rog!

Answer 1

$a) \frac{123!}{121!}= \frac{121!*122*123}{121!}=122*123= 15006 \\ b) \frac{2753!}{2752!} = \frac{2752!*2753}{2752!} =2753 \\ c) \frac{(n+1)!}{n!}= \frac{n!(n+1)}{n!}= n+1 \\ d) \frac{(n+3)!}{n!(n+3)}= \frac{n!(n+1)(n+2)(n+3)}{n!(n+3)}=(n+1)(n+2)=n^2+3n+2 \\ e) \frac{(n+1)!*n!}{(n-1)!(n+2)!}= \frac{(n-1)!*n*(n+1)*n!}{(n-1)!*n!*(n+1)*(n+2)}= \frac{n}{n+2}$