Question

Сочетания. Реши уравнение

Answer 1

$2*C_{x}^{x-2}-4C_{x}^{1}=6\\\\2*\frac{x!}{(x-2)!*(x-x+2)!}-4x=6\\\\2*\frac{(x-2)!*(x-1)*x}{(x-2)!*2}-4x=6\\\\x(x-1)-4x=6\\\\x² - x - 4x - 6 = 0\\\\x^{2} -5x-6=0\\\\x_{1}=6\\\\x_{2}=-1-neyd\\\\Otvet:\boxed{6}$