A cylinder is obtained by revolving a rectangle about the $x-$axis,the base of the rectangle lying on the $x-$axis and the entire rectangle lying in the region between the curve $y=\frac{x}{x^2+1}$ and the $x-$axis.Find the maximum volume of the cylinder.
I could not solve this problem,i could not understand clearly the problem,how a rectangle can lie between $y=\frac{x}{x^2+1}$ and the $x-$axis and how to find the max volume.Please help me.