What is the surface area of the solid created by revolving #f(x) = e^-x+e^(x) , x in [1,2]# around the x axis?
If we imagine this solid being broken into small cylindrical slices (as we do for finding volumes of solids of revolution), we realize that the surface area of each of these solids is
The small length
So, we integrate, since the radius of the solid is just
Using u-sub, with