x^2+3*x*y+y^2=31, x*y-6=0 система, помогите пожалуйста

x^2+3*x*y+y^2=31

x*y=6

(x+y)^2=31-xy=25

(x+y)=5

xy=6      x=2 y=3

              x=3 y=2

x+y=-5

xy=6

x=-2 y=-3

x=-3 y=-2

x^2+3*x*y+y^2=31

x*y=6

(x+y)^2+x*y=31

(x+y)^2=25

Решаем 2 системы:

x+y=5                             x+y=-5

x*y=6                              x*y=6

x=5-y                               x=-y-5

(5-y)*y=6                        -(5+y)y=6

y^2-5y+6=0                    y^2+5y+6=0

y = 2  x=3                        y=-3    x=-2

y= 3   x=2                        y=-2    x=-3