(x^-1)+(y^-1)/1-(x^-1)(y^-1) 明天就要交,十万火急,

(x+y)(x-y)+4(y-1) [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y x>=1,x-y y=x-1(x 计算：(1+ y/x-y )·(1- x/x+y) (x/x+y-x/y-x-2xy/x.x-y.y)/(1/x-1/y) 分式化简 感激不尽1.x,y满足(x-y-1)(x+y) (1-y+x/y)除以y平方-x平方/x 证明:(y/x)+(x/y)+xy≥x+y+1 x+y分之1-(x+y)的平方x-y 求导 y=[x/(1+x)]^x 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 3（x-1)³y-（1-x）³z m(x-y)²-x+y x²(x+y)(y-x)-xy(x+y)(x-y) 因式分解 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) 1/(x-y)/(1/y-/x) 因式分解：（1+x+y)(1-x-y) (x+5y)(x-7y-1)