已知4x-4x²y-xy²+y³=0,求(x²+y²)/xy
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
已知X²+Y²+X²Y²-4XY+1=0 求:(X-Y)^2008-(XY)^2
已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
2x+y=0,求4x²+2xy(x+y)+y³
已知非零有理数x,y满足x²-4xy+4y²=0,求x-y/x+y-y-x/x+y的值.
已知2x+y=0,求x-2y/x²+xy*(x²-y²)/x²-4xy+4y
已知2x+y=0,求x-2y/x²+xy乘(x²-y²)÷x²-4xy+4y
已知2X-3√xy-2y=0(x>0)求2x²+xy-9y²分之x²+4xy-16y
已知X²+3XY-4Y²=0(Y≠0)求X-Y/X+Y
已知:x/y=4/5,求y²/(x²-xy+y²)的值
已知x²-4xy+4y²=0,且xy≠0,那么x-y/x+y