Решите уравнения( сложением и подстановкой)

1) [latex] \left \{ {{ \frac{x+y-xy}{xy(x+y)} = \frac{1}{2} } \atop {xy(x+y)=2}} \right. \\ \left \{ {{ x+y-xy = 1} \atop {xy(x+y)=2}} \right.\\ \left \{ {{ (x-1)(1-y)=0 } \atop {xy(x+y)=2}} \right.\\[/latex] 1) x = 1 y(1+y)=2 y² + y - 2 = 0 D = 1 + 8 = 9 y₁ = (-1-3)/2=-2 y₂ = (-1+3)/2=1 Ответ: (-2; 1); (1; -2); (1; 1) 2)[latex] \left \{ {{x(1+y)=3} \atop {xy^2(1+y)=12}} \right. \\ \left \{ {{x(1+y)=3} \atop {3y^2=12}} \right. \\[/latex] y²= 4 y₁ = -2 y₂ = 2 x₁(1-2)=3 x₁ = -3 x₂(1+2)=3 x₂ = 1 Ответ: (-3; -2); (1; 2)