{x+y=7,x²+y²=25 {x²+y²=20,x²-5xy+6y
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
已知x+y=1,xy=-二分之一,求x(x+y)(x-y)-x(x+y)²
x²+xy/(x-4y)(x+y),其中x=4,y=-1
x²/xy-x/y
已知实数x,y,xy=5,x+y=7,求代数式x²y+xy²的值
已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy
已知xy²=-6,求xy(x^3y^7-3x^2y^5-11.5y)的值
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.
x/y=3,求x²+y²-xy/x²-y²的值.
已知实数x,y满足5x²+2y²+1=6xy+4x-2y,则x²-xy+2000y
2x+y=0,求4x²+2xy(x+y)+y³