Question

решить систему x+y=2 xy=-8​

Answer 1

Ответ:

$x + y = 2 \\ xy = - 8 \\ \\ x = 2 - y \\ xy = - 8 \\ \\ (2 - y)y = - 8 \\ 2y - {y}^{2} = - 8 \\ - {y}^{2} + 2y + 8 = 0 \\ d = 4 - 4 \times ( - 1) \times 8 = 36 \\ y1 = - \frac{ - 2 + 6}{ - 2} = - 2 \\ y2 = \frac{ - 2 - 6}{ - 2} = 4 \\ x1 = 2 + 2 = 4 \\ x2 = 2 - 4 = - 2$

(х¹, у¹)= (4,-2)

(х²,у²)= (-2,4)