What is the antiderivative of ln(x)/x?

1 Answer
Apr 1, 2015

(ln(x))^2/2+C(ln(x))22+C (Also written 1/2ln^2(x)+c12ln2(x)+c).

Explanation:

ln(x)/x=ln(x)*(1/x)ln(x)x=ln(x)(1x).

The derivative of lnxlnx is 1/x1x, so

ln(x)*(1/x)ln(x)(1x) is of the form: f(x)*f'(x), so the antiderivative is 1/2 (f(x))^2 +C.

(Alt notation: ln(x)/x=ln(x)*(1/x) is of the form u (du)/(dx) whose antiderivative is u^2/2 +C.)