Помогите с системой {Х+У=2 внизу {ХУ=-15

Question

Помогите с системой {Х+У=2 внизу {ХУ=-15

Answer 1

X + y = 2
xy = - 15

x = 2 - y
(2 - y)y + 15 = 0 *

- y^2 + 2y + 15 = 0 /:(-1)
y^2 - 2y - 15 = 0 
D = 4 + 60 = 64
y1 = ( 2 + 8)/2 = 10/2 = 5
y2 = ( 2 - 8)/2 = - 6/2 = - 3

x1 = 2 - y1 = 2 - 5 = - 3 
y1 = 5

x2 = 2 - y2 = 2 + 3 = 5
y2 = - 3 

Ответ
( - 3; 5) ;(5 ; - 3)