Question

Решите уравнение:
$\frac{120}{x} - \frac{120}{x+20} = 1$

Answer 1

$\frac{120}{x} - \frac{120}{x+20} =1~~ |*x(x+20) \\ \\ 120(x+20)-120x=x(x+20) \\ 120x+2400-120x=x^2+20x \\ 2400=x^2+20x \\ x^2+20x-2400=0 \\ D=400-4*(-2400)=400+9600=10000 \\ x_1= \frac{-20+100}{2} = \frac{80}{2} =40 \\ x_2= \frac{-20-100}{2} = \frac{-120}{2} =-60$

Ответ:  $-60;~40$