Question

Решите систему уравнений x-xy=8
y+3x=-1

Answer 1

Ответ:

$x - xy = 8 \\ y + 3x = - 1 \\ \\ x = \frac{8}{1 - y} \\ y + \frac{3 \times 8}{1 - y} = - 1 \\ \\ 24 = - (1 + y)(1 - y) \\ 24 = - 1 + {y}^{2} \\ {y}^{2} = 25 \\ y 12= + - 5 \\ x = \frac{8}{1 - y} \\ x1 = \frac{8}{6} \\ x2 = - 2$

Проверим

Х=-2 у=5

-2+2*5=8

5-6=-1

х=8/6 у=-5

8/6+40/6=48/6=8

-5+24/6=-5+4=-1