Hi. Could someone please help me figure out this integral, which I am doing for extra practice. (I'm doing terribly on integrals overall, and hoping some extra practice will help.) I need to get the integral of this function:

x / sqrt (9 - x^2)

Because of the chapter this problem is in, I think it is solved working with u-substition and the integral of the natural logarithm function, but I can't seem to make it work.