4X+2Y=185X+Y=0

已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y* 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& 已知x^2+4y^2-4x+4y+5=0,求(y^4-x^4)/(y-2x)(x+y)*2x-y 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} .先化简再求值：（2x+y）（2x+y)-(2x-y)平方其中X,Y满足X平方+Y平方-2X+4Y+5=0 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 设Z=X+Y,其中X,Y满足X+2Y>=0,X-Y x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20