Question
Integrate the function x (log x)2

Answer

Let $I=x(\log x)^{2}$ 
Integrating by parts, we get,
$I=\left[(\log x)^2 \int x d x-\int\left\{\left(\frac{d}{d x} (\log x)^2 \right) \int x d x\right\} d x\right]$ 
= $\left[\frac{x^{2}}{2}(\log x)^2-\int \frac{2 \log x }{x} \cdot \frac{x^{2}}{2} d x\right]$ 
= $\frac{x^{2}}{2}(\log x)^{2}- \int x \log x \cdot d x$ 
= $\frac{x^{2}}{2}(\log x)^{2} - [ log x ∫ x dx -∫( \frac {d}{dx} (log x)∫ x dx) dx]$
= $\frac{x^{2}}{2}(\log x)^{2} - [ \frac {x²}{2}\log x - ∫(\frac1x \cdot\frac{x^2}{2} ) dx$
= $\frac{x^{2}}{2}(\log x)^{2}-\frac{x^{2}}{2} \log x+\frac{x^{2}}{4}+C$

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