Question
$\int_3^5 \frac{d x}{\sqrt{x+4}+\sqrt{x-2}}$

Answer

$
\begin{aligned}
& \int_3^5 \frac{d x}{\sqrt{x+4}+\sqrt{x-2}} \\
& =\int_3^5 \frac{1}{\sqrt{x+4}+\sqrt{x-2}} \times \frac{\sqrt{x+4}-\sqrt{x-2}}{\sqrt{x+4}-\sqrt{x-2}} d x \\
& =\int_3^5 \frac{\sqrt{x+4}-\sqrt{x-2}}{x+4-x+2} d x \\
& =\frac{1}{6} \int_3^5\left[(x+4)^{\frac{1}{2}}-(x-2)^{\frac{1}{2}}\right] d x \\
& =\frac{1}{6}\left[\frac{(x+4)^{\frac{3}{2}}}{\left(\frac{3}{2}\right)}-\frac{(x-2)^{\frac{3}{2}}}{\left(\frac{3}{2}\right)}\right]_3^5 \\
& =\frac{1}{9}\left[(x+4)^{\frac{3}{2}}-(x-2)^{\frac{3}{2}}\right]_3^5 \\
& =\frac{1}{9}\left[\left(9^{\frac{3}{2}}-3^{\frac{3}{2}}\right)-\left(7^{\frac{3}{2}}-1\right)\right] \\
& =\frac{1}{9}(27-3 \sqrt{3}-7 \sqrt{7}+1) \\
& =\frac{1}{9}(28-3 \sqrt{3}-7 \sqrt{7}) .
\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