X(y+z)=2, y(x+z)=-28, z(x+y)=-10. найдите x,y,z.

Xy+zx =2
yx+yz= -28
zx+yz = -10

xy = 2-zx
2-xz + yz = -28  -> xz = 30 + yz
30+yz + yz = -10  -> yz = -20 -> xz = 10 -> xy = -8
yz/xz = -2 и xy = -8 -> y = -+4 , x = +-2  -> z = +-5