What is the antiderivative of
$\int\frac{1}{r \ln(r)} \ dr$
I'm trying to use substitution, but substituting $u=r$ doesn't help as that just changes the variable.
What is the antiderivative of
$\int\frac{1}{r \ln(r)} \ dr$
I'm trying to use substitution, but substituting $u=r$ doesn't help as that just changes the variable.
As suggested in the comments, try the substitution $u = \ln (r)$. Then, $du = \frac{1}{r} \ dr$.
$\int\frac{1}{r \ln(r)} \ dr = \int\frac{du}{u} = \ln(u) + C = \ln\left(\ln(r)\right) + C$
Consider the substitution $u=\ln(r)$,
Then $u'=\frac1r$
Have you tried that?