Question

Questão 22) Efetue :

Answer 1

$\boxed{a) \frac{11!+9!}{10!}=\frac{11.10.9!+9!}{10.9!}=\frac{9!(11+1)}{10.9!}=\frac{12}{10}=\frac{6}{5}}$

$\boxed{b) 17!-17.16!=17!-17!=0}$

$\boxed{c) \frac{40!-39!}{41!}=\frac{40.39!-39!}{41.40.39!}=\frac{39!(40-1)}{41.40.39!}=\frac{39}{1640}}$

$\boxed{d) \frac{(85!)^2}{86!83!}=\frac{85!.85!}{86!83!}=\frac{85!85.84.83!}{86.85!83!}=\frac{85.84}{86}}$