Question

Решите систему уравнений:
{x²+y²+x+y=18
{x²-y²+x-y=6

Answer 1

$left { {{x^2+y^2+x+y=18} atop {x^2-y^2+x-y=6}} right. \ ------------\ 2x^2+2x=24\ \x^2+x-12=0 \ \ D=49=7^2;x_{1} =-4;x_{2}= 3\ \ 1)x=-4\ \ 16+y^2-4+y=18\ \ y^2+y-6=0;(y-2)(y+3)=0\ \ y_{1} =-3;y_{2} =2\ \ (-4;-3) (-4;2)\ \ 2)x=3\ \ 9+y^2+3+y=18\ \y^2+y-6=0;(y-2)(y+3)=0\ \ y_{3} =-3;y_{4} =2\ \ (3;-3) (3;2)\ \ otvet: (-4;-3) (-4;2)  (3;-3) (3;2)$