{ x-y =3√5 ; x² -xy -y² = -5⇔{ x-y =3√5 ; x(x -y) -y² = - 5.
{ x-y =3√5 ; 3√5*x -y² = - 5. { y= x- 3√5 ; 3√5*x -(x- 3√5)² = - 5.
3√5*x -(x- 3√5)² = - 5 ;
3√5*x -x²+6√5*x -45 = - 5 ;
x²-9√5x + 40 = 0 ;
x₁ =(9√5 - 7√5)/2 = √5⇒y₁ =√5 -3√5 = -2√5.
x₂=(9√5 + 7√5)/2 = 8√5 ⇒y₂ =8√5 -3√5 =5√5.
ответ : (√5 ; -2√5) , (8√5 ; 5√5 ).