Question

Срочно помогите прошу

Answer 1

$1) \ A_{5} ^{3}=\dfrac{5!}{(5-3)!}=\dfrac{5!}{2!}=\dfrac{2!\cdot3\cdot4\cdot5}{2!}=3\cdot 4\cdot 5=\boxed{60} \\\\\\2) \ A_{35} ^{2}=\dfrac{35!}{(35-2)!}=\dfrac{35!}{33!}=\dfrac{33!\cdot34\cdot35}{33!}=34\cdot35=\boxed{1190} \\\\\\3) \ \dfrac{P_{7} }{P_{2} }=\dfrac{7!}{2!}=\dfrac{2!\cdot3\cdot4\cdot5\cdot6\cdot7}{2!}=3\cdot4\cdot5\cdot6\cdot7=\boxed{2520} \\\\\\A_{17} ^{3}=\dfrac{17!}{(17-3)!} =\dfrac{17!}{14!}=\dfrac{14!\cdot15\cdot16\cdot17}{14!}=15\cdot16\cdot17=\boxed{4080}$