Решить систему уравнений по алгебре

{ x - y + xy = 2
{ x^2 + y^2 - xy = 8
=>
{ x - y = 2 - xy
{ x^2 - 2xy + y^2 = 8 - xy
=>
{ (x - y) = 2 - xy
{ (x - y)^2 = 8 - xy
=>
{ xy = 2 - (x - y)
{ xy = 8 - (x - y)^2
=>
2 - (x - y) = 8 - (x - y)^2 ------> (x - y) = t
t^2 - t - 6 = 0 ------> t1 = -2; t2 = 3
=>
(x - y) = t1 = -2 -----> x1 = y - 2
(x - y) = t2 = 3 -------> x2 = 3 + y
=> из условия:
при x1 = y - 2
{ x - y + xy = 2
(y-2) - y + (y-2)*y = 2
y - 2 - y + y^2 - 2y = 2
y^2 - y - 4 = 0 ----------> y(1,2) = (1 + - V17)/2
при x2 = 3 + y
(3+y) - y + (3-y)*y = 2
3 + y - y + 3y - y^2 = 2
y^2 - 3y - 1 = 0 ----------> y(3,4) = (3 + - V13)/2