Question

(Фигурная скобка)X-Y=5,

                                   X²+Y²=81-2xy

Answer 1

x = 5 + y

(5+y)^2 + y^2 - 81 + 2y(5+y) = 0
25 + 10y + y^2 - 81 + 2y(5+y) = 0
4y^2 + 20y - 56 = 0
y^2 + 5y - 14 = 0
y1 = 7 y2 = -2

y1 = 7
x1 = 12

y2 = -2
x2 = 3