You could have made life a bit easier for yourself by using properties of logarithms. In fact, , so . Then when you differentiate, the first term is constant, so it disappears and you only have to deal with the second term.
You could have made life a bit easier for yourself by using properties of logarithms. In fact, , so . Then when you differentiate, the first term is constant, so it disappears and you only have to deal with the second term.