求y=x^2+2x+1/(x^2+2x+3)的最小值拜托了各位

y=(2x*x-2x+3)/(x*x-x+1),求值域? 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 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 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 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) x+2y=2x+y+1=7x-y 求：2x-y? (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 若x*x+y*y=x+y-1/2,求x,y的值如题 求y=(x^2)+2x(x≥0) y=-x+2x(x 求反函数y=x^2-2x,x>1 求y =2^x -1/x+1在x 求y=(5x-1)/(4x+2) (x y=x*x-2x+1求导数 y=(X+1)(X+2)(X+3)求导数 y=x+1/x(x>2)值域怎么求 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)