Система: х+у=5

2 х-у²=7

Х = 5 - y

2 * (5 - y) - y^2 = 7

10 - 2y - y^2 = 7

Y^2 + 2y - 3 = 0

D = 4 + 12 = 16; кв. корень 16 = 4

Y1 = ( - 2 + 4) : 2 = 1

Y2 = ( - 2 - 4) : 2 = - 3

X = 5 - y

X1 = 5 - 1 = 4

X2 = 5 + 3 = 8

Ответ (4; 1); (8; - 3)