m+2mn+2n平方-6n+9=0,求m和n的值,另一个问题,x+2y-2xy+4y+4=0,求x得y次方 快,谢了哦

m+2mn+2n-6n+9=0 m+2mn+n+n-6n+9=0 (m+n)+(n-3）=0 又(m+n)≥ 0；(n-3）≥0；且(m+n)+(n-3）=0 则：m=-n n=-3 故：m =3 ② x+2y-2xy+4y+4=0 （x-2xy+y）+(y-+4y+4)=0 (x-y)+(y+2)=0 又(x-y) ≥ 0；(y+2) ≥0；且(x-y)+(y+2)=0 则：x-y =0 y+2 =0 故：x=y y=-2 则：x=-2 ,y=-2