What is the antiderivative of ln(x3)x?

1 Answer
Dec 3, 2016

32(ln(x))2+C

Explanation:

This is the same as asking:

ln(x3)xdx

Using the logarithm rule log(ab)=blog(a) we can move the constant out. Then, a good substitution would be u=ln(x), which implies that du=1xdx (see this through taking the derivative of ln(x)).

=3ln(x)xdx=3ln(x)(1xdx)=3udu=3u22=32(ln(x))2+C

We see that integration by parts isn't even necessary!