Question

система уравнений x-y=-7, xy-4y+x-4=0

Answer 1

x-y=-7
xy-4y+x-4=0

x= y - 7
y(y - 7) - 4y+(y - 7) - 4=0

y² - 7y - 4y +y - 7 - 4 =0

y² - 10y -11 =0

D= 100+44= 144

y₁ = 10+12/2 = 11

у₂= 10 - 12/2 = -1

х₁= 4
х₂= -8.

Ответ: (4;11) и (-8; -1).