QuestionIf we perform the appropriate (i.e. helpful) $u$-sub for $\int \frac{\ln (x)}{x} \mathrm{dx}$, what does the new integral look like in terms of $u$ right after performing the substitution? $\int \frac{\ln (u)}{u} d u$ $\int u d u$ none of these $\int \frac{\ln (u)}{x} d u$