How do you integrate int ln(x)/x dxln(x)xdx using integration by parts?

1 Answer
Dec 20, 2015

intln(x)/xdx = ln(x)^2/4ln(x)xdx=ln(x)24

Explanation:

Integration by parts is a bad idea here, you will constantly have intln(x)/xdxln(x)xdx somewhere. It is better to change the variable here because we know that the derivative of ln(x)ln(x) is 1/x1x.

We say that u(x) = ln(x)u(x)=ln(x), it implies that du = 1/xdxdu=1xdx. We now have to integrate intuduudu.

intudu = u^2/2udu=u22 so intln(x)/xdx = ln(x)^2/2ln(x)xdx=ln(x)22