求y=x^2-x+1/2x^2-2x+3的值域,

y=(2x*x-2x+3)/(x*x-x+1),求值域? 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) y=(X+1)(X+2)(X+3)求导数 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 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=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x y=x^x的导函数是：y'=x^x(Inx+1)我知道怎样求.但为什么不可以这样求.y=x^x=x*x*x*x*x*x*...*x(x个x) 则y'=(x')*x^(x-1)+x*(x')*x^(x-2)+.=x^x 已知x(x+1)-(x²+y)=3求2/x²+y²-xy 求方程 dy/dx+x(y-x) +x^3(y-x)^2=1的通解~ 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 x+2y=2x+y+1=7x-y 求：2x-y?