Question

решить систему уравнений xy=-2

                                          x-2y=5

Answer 1

КОРни:
1   и -2 подставь всё верно

Answer 2

{ xy = -2

{ x - 2y = 5

 

{ (5 + 2y)y = -2

{ x = 5 + 2y

 

2y² + 5y + 2 =0

D = 25 - 4 * 2 * 2 = 25 - 16 = 9

y1 = (-5 + 3) / 4 = -2/4 = -1/2 = -0.5

y2 = (-5 - 3) / 4 = -8/4 = -2

Тогда  x1 = 5 + 2 * (-0.5) =5 - 1 = 4

          x2 = 5 + 2 * (-2) = 5 - 4 = 1

Ответ: x = 4, y = -0.5;     x = 1, y = -2