x*x+3xy-4y*y=0 求（x-y）/（x+y）给点思路就行

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,y>0 2x+y+3=xy 求5x+4y最小值 x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 已知3x*x-xy-4y*y=0(x#y),求x/y的值 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*y)的值 已知2x+3y=0,求代数式1.5x+4y/3x-2y 2.x²+xy-y²/x²-xy+y² 已知（x+2）^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy 已知：（x+2)²+|x+y-2|=0,求3x²y+{-2x²y-[-2xy+(x²y-4x²）]-xy} 已知x的平方+y的平方-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y) 已知x²+y²-8x+6y+25=0,求（x-y+4xy/x-y）（x+y-4xy/x+y） 已知x^2+3xy-4y^2=0(y≠0),求x-y/x+y的值.已知x^2+3xy-4y^2=0(y≠0),求x-y/x+y的值. 已知X²+3XY-4Y²=0（Y≠0）求X-Y/X+Y 已知x方+3xy-4y方=0（y不等于0）求x-y/x+y x^2+4y^2-6x+4y+10=0,求x^4-y^4/(x+2y)(x-2y)*x+2y/xy^2+y^3除以（x^2+y^2/y)^2的值 已知x-3y=0,求(2x+y)/(x^2-2xy+y^2)X(x-y) 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}/x^2-9y^2的值 已知/X-Y-1/+(XY+3)的平方=0,求(-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY)的值!已知/X-Y-1/+(XY+3)的平方=0,求(-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY)的值急! 已知(4x-3y)(4x-3y)=(3x-2y)(3x-2y),并且xy不等于0,求x除以的y值