Question

Сделайте 5 номер ток!!

Answer 1

Ответ:

(12; 5)

Пошаговое объяснение:

$dfrac{x!}{2!(x-2)!}=66\\ x(x-1)=132\\x^2-x-132=0\\D=1+528=529\\x=(1+23)/2=12$

$dfrac{x!}{y!(x-y)!} =dfrac{x!}{(y+2)!(x-y-2)!}\\ y!(x-y)!=(y+2)!(x-y-2)!\\(x-y-1)(x-y)=(y+2)(y+1)\\(11-y)(12-y)=(y+2)(y+1)\\132-23y+y^2=y^2+3y+2\\26y=130\\y=5$