y=(x-x^3)/(1+2x^2+x^4)的最大最小值怎么求?

函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 3^x+2x=y,x y=(2x*x-2x+3)/(x*x-x+1),求值域? 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 计算：1-2x+x^2/x-x^3*xy+x^2y/x-x^2 [2/3x-2/x+y(x+y/3x-x-y)]/x-y/x