If $\int \frac{\sqrt{x}}{x(x+1)} d x=k \tan ^{-1} m+c$, (where $c$ is constant of integration), then
If $\int \frac{\sqrt{x}}{x(x+1)} d x=k \tan ^{-1} m+c$, (where $c$ is constant of integration), then
- $\mathrm{k}=1, \mathrm{~m}=\sqrt{\mathrm{x}}$
- $\mathrm{k}=2, \mathrm{~m}=\sqrt{\mathrm{x}}$
- $\mathrm{k}=1, \mathrm{~m}=\mathrm{x}$
- $\mathrm{k}=2, \mathrm{~m}=\mathrm{x}$
Solution
$I=\int \frac{\sqrt{x}}{x(x+1)} d x$
Put $x \tan ^2 \theta \Rightarrow d x=2 \tan \theta \sec ^2 \theta d \theta$
$\begin{aligned}
& \therefore I=\int \frac{\tan \theta\left(2 \tan \theta \sec ^2 \theta\right)}{\tan ^2 \theta(1+\tan \theta)} d \theta \\
& =2 \int \frac{\sec ^2 \theta}{\sec ^2 \theta} d \theta=2 \int d \theta=2 \theta \\
& =2 \tan ^{-1} \sqrt{x}+c
\end{aligned}$
Comparing with given data, $\mathrm{k}=2, \mathrm{~m}=\sqrt{\mathrm{x}}$
Asked in: MHT CET 2021 (24 Sep Shift 1)
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