Answer
$$\frac{1}{3}(\ln x)^3+c.$$
Work Step by Step
Let $ u=\ln x $, then $ du= \frac{1}{x} dx $ and hence
$$\int \frac{(\ln x)^2 }{x}dx = \int u^2du=\frac{1}{3}u^3+c\\
=\frac{1}{3}(\ln x)^3+c.$$
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