Приведем к общему знаменателю x(x+5)
[block](1200(x+5))/(x(x+5)) - (1200x)/(x(x+5)) = 8[/block]
[block](1200(x+5) - 1200x)/(x(x+5)) = 8[/block]
[block](1200x+6000 - 1200x)/(x(x+5)) = 8[/block]
[block](6000)/(x(x+5)) = 8[/block]
6000= 8x(x+5)
6000= 8x^2+40x
8x^2+40x-6000 = 0
Сократим на 8
x^2 + 5x - 750 = 0
D = 5^2 + 4*750 = 3025
sqrt(D) = sqrt(3025) = 55
[block]x_1 = (-5+55)/(2) = 25[/block]
[block]x_2 = (-5-55)/(2) = -30[/block]
Ответ: -30 и 25