Question

simplifique:
a)30!/28!2!
b) k!/(k-1)!
c)10!/5!7!

Answer 1

a)$\frac{30!}{28!2!} = \frac{30.29.28!}{28!2!}=\frac{30.29}{2.1}=15.29=435$

b)$\frac{k}{(k -1)!}=\frac{k.(k - 1)!}{(k -1)!}=k$

c)$\frac{10!}{5!7!}=\frac{10.9.8.7!}{5!.7!}=\frac{10.9.8}{5.4.3.2.1}=3.2=6$