Need some help with this indefinite integral:
The answer I got was d/m (ln(mx+k)) by using u = mx+k.
d is not a constant. "dx" means that you are integrating the function with respect to x!
its..
$\displaystyle \int \frac{1}{mx+k} dx $
so when you substituted $\displaystyle u = mx+k$, you should have gotten:
$\displaystyle du = m dx \implies dx = \frac{1}{m} du$
then you substitute $\displaystyle dx = \frac{1}{m} du$ in your question to get:
$\displaystyle \frac{1}{m} \int \frac{1}{u} du$
do you get it?