1.(1+y/x)/(1-y/x) 化简 2.已知x/y=3,求（x的平方+2xy-3y的平方）/（x的平方-xy+y得平方）是初二分式的题,3.化简a-b/a+b

感激不尽1.x,y满足(x-y-1)(x+y) (x+y)(x-y)+4(y-1) 化简(2x+y)(2x-y)-(x+2y)(x-2y-1) 2x分之1- x+y分之1(2x分之x+y -x-y)化简 化简1/2x-1/x+y（x+y/2x-x-y） [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 1/(x-y)+1/(x+y)+2x/(x^2+y^2)+4x^3/(x^4+y^4)化简 化简：[(2x-y)平方+（2x+y)(2x-y)-4x(x-y+1)]÷2x |x-y|+|y+1|=0化简 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) y'/y=1/x x^/y-x-y^/y-x化简. 化简x(y-x)-y(x-y) 计算：(1+ y/x-y )·(1- x/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