Решите систему уравнений x+y=-5
xy+6=0
Методом подстановки

x + y = - 5 \\ xy + 6 =0 \\ \\ x = - 5 - y \\ xy + 6 = 0 \\ \\ ( - 5 - y) \times y + 6 = 0 \\ - 5y - {y}^{2} + 6 = 0 \\ {y}^{2} + 5y - 6 = 0 \\ d = 25 - 4 \times 1 \times ( - 6) = 49 \\ y1 = \frac{ - 5 + 7}{2} = 1 \\ y2 = \frac{ - 5 - 7}{2} = - 6 \\ \\ x1 = - 5 - 1 = - 6 \\ x2 = - 5 - ( - 6) = 1