x+2y+5=22 4x=y 求x= y= z=

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-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*y)的值 已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知：4x = 5y,求(x+y) ：y x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x*x+y*y-2x+4y+5=0求x, 如果|X|=4 |Y|=2 且|X+Y|=X+Y 求X+Y 求(X+Y)(X-Y)(X²+Y²),X=5 Y=2, (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知x^2+y^2-2x+4y+5=0.求{(x^4-y^4)/[(x+y)(2x-y)]}*{[(2x-y)/(xy-y^2)]}/{[x^2+y^2]/y}^2 4x+2y=22 4x+y=30 求x和y 已知x²+4y²-4x+4y+5=0,求：(x^4-y^4)/[(2x-y)(x+y)]*(2x-y)/(xy-y²)/[(x²+y²)²/y²]