No, that is incorrect and I don't think this can by integrated in terms of elementary functions. What you have done, integrating [itex]u^{1/2}[/itex] as [itex](3/2)u^{3/2}[/itex] and then dividing by the derivative of u, can only be done if u is linear so that u' is a constant. Constants can be "moved" inside and outside of an integral. functions of the variable of integration cannot.