Question

Решите систему уравнения 2x - y =5 и x2 + y + 2 = 0

Answer 1

$\left \{ {{2x - y = 5} \atop {x^2 + y + 2 = 0}} \right. \\ \\ \left \{ {y = 2x - 5} \atop {x^2 + y + 2 = 0}} \right. \\ \\ \left \{ {y = 2x - 5} \atop {x^2 + 2x - 5 + 2 = 0}} \right. \\ \\ \left \{ {y = 2x - 5} \atop {x^2 + 2x - 3= 0}} \right.$
Решим второе квадратное уравнение:
$x^2 + 2x - 3 = 0 \\ x_1 + x_2 = -2 \\ x_1 \cdot x_2 = -3 \\ \\ x_1 = -3 \\ x_2 = 1$
$\left \{ {{x = -3} \atop {-6 - y = 5 }} \right. \ \ \ \ \ \ \ \ \ \ \ \ \ \left \{ {{x=1} \atop {2 - y = 5}} \right. \\ \left \{ {{x = -3} \atop {y = -11}} \right. \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \left \{ {{x = 1 \atop {y = -3 }} \right.$
ответ: $\boxed{(-3; -11), (1; -3).}$