Question
$\int_1^3 x^2 \log x d x$

Answer

$
\begin{aligned}
& \int_1^3 x^2 \log x d x=\int_1^3(\log x) \cdot x^2 d x \\
= & {\left[(\log x) \int x^2 d x\right]_1^3-\int_1^3\left[\frac{d}{d x}(\log x) \int x^2 d x\right] d x } \\
= & {\left[(\log x)\left(\frac{x^3}{3}\right)\right]_1^3-\int_1^3 \frac{1}{x} \times \frac{x^3}{3} d x } \\
= & \frac{1}{3}\left[x^3 \log x\right]_1^3-\frac{1}{3} \int_1^3 x^2 d x \\
= & \frac{1}{3}[27 \log 3-0]-\frac{1}{3}\left[\frac{x^3}{3}\right]_1^3 \quad \ldots[\because \log 1=0] \\
= & 9 \log 3-\frac{1}{9}(27-1) \\
= & 9 \log 3-\frac{26}{9} .
\end{aligned}
$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free