What is the antiderivative of (ln x)^2(lnx)2?

1 Answer
Feb 19, 2015

Hello,

The answer is x (ln x)^2 - 2x ln x + 2xx(lnx)22xlnx+2x.

You have to know that antiderivative of ln xlnx is xln x - x + cxlnxx+c.

Use integration by parts : int u'v = uv - int uv'.

int ln x \cdot ln x \ dx = ln x \cdot (x ln x - x) - int 1/ x (x ln x - x)

So,

int ln x \cdot ln x \ dx = x (ln x)^2 - x ln x - int (ln x - 1)

and then,

int ln x \cdot ln x \ dx = x (ln x)^2 - x ln x - (x ln x - x - x) + c

and then int ln x \cdot ln x \ dx = x (ln x)^2 - 2x ln x + 2x + c