已知y-2x=0,求代数式(x^+xy+y^)(x^—y^)/(x^-y^)(x^-xy+y^)
已知x+y=-1,xy=-2,求代数式-5(x+y)+(x-y)+x(xy+y)的值
已知x^2-3y^2=2xy(x>0,y>0),求代数式x+2y/x-y
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=-1,xy=-2,求代数式-5(x+y)+(x-y)+2(xy+y)的值
已知X+Y=-1,xy=-2,求代数式-5(x+y)+(x-y)+(xy+y)的值
已知xy/x+y=2,求代数式3x-5y+3y/-x+3xy-y
已知:x-xy=40,xy-y=-20,求代数式x-y和x+y-2xy的值.
已知xy/x+y=3,求代数式2x-5xy+2y/x-3xy+y
已知xy/x+y=2,求代数式3x-5xy+3y/-x+2xy-y的值
已知x-y=2xy,求代数式3x-5xy-3y/x+xy-y的值
已知xy/x+y=2,求代数式3x-xy+3y/-x+3xy-y的值
已知y=根号下(x-4)+根号下(4-x)+3,求代数式(x-y+4xy/x-y)(x+y-4xy/x+y)?