-(x+1)/(x-y)=(x-1)/(x-y) 变形对吗

求导 y=[x/(1+x)]^x x>=1,x-y y=x-1(x z=0.015x*x+y*x*0.05+(1-x-y)*2.5*(x+y) x>0.35.xy>0.70x+y y'-(1/x)y=xe^-x 求导：y=(ln x)^x + x^(1/x) 函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x y=3x/x²+x+1(x 函数y=2x/x²-x+1（x 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 x.y都是自然数,且x(x-u)-y(y-x)+12,求x.y得值快1且x(x-y)-y(y-x)=12 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x+y=86/x+x/y=1 y=x²-x y=x-1 y=(2x)/x-1化简成用y表示x 已知x,y满足{x>=1,x+y 已知x,y满足{x>=1,x+y