Question

ПОЖАЛУЙСТА ПОМОГИТЕ!

Answer 1

$\left \{ {{x = y^{2} - 4y} \atop {x + y = 4}} \right. \left \{ {{x = y^{2} - 4y} \atop {x = 4 - y}} \right. \left \{ {{4 - y= y^{2} - 4y} \atop {x = 4 - y}} \right. \\4 - y = y^{2} - 4y\\y^{2} + y - 4y - 4 = 0\\y^{2} - 3y - 4 = 0\\y_{1} = -1; y_{2} = 4\\x_{1} = 4 - y_{1} = 4 + 1 = 5; x_{2} = 4 - y_{2} = 4 - 4 = 0;\\ (5; -1); (0; 4).$