[질문] x^2-xy-2y^2=0 2x^2+y^2=9 연립방정식 풀어주세요

x^2-xy-2y^2=(x+y)(x-2y)=0. x=-y,2y. 1)x=-y 2y^2+y^2=3y^2=9. y^2=3. <<y=루뜨3,x=-루뜨3>> 2)x=2y 2x^2+y^2=8Y^2+y^2=9y^2=9. y^2=1 <<y=1 x=2>>감사합니다^^