Evaluate the following integrals:
$\int \frac{x+\sqrt{x+1}}{x+2} d x$
The given equation can be written as
$\Rightarrow \int \frac{x}{x+2} d x+\int \frac{\sqrt{x+1}}{x+2} d x$
First integration be $l 1$ and second be $l 2$.
$\Rightarrow$ For l1
Add and subtract 2 from the numerator
$\Rightarrow \int \frac{x+2-2}{x+2}$
$\Rightarrow \int \frac{x+2}{x+2} \cdot d x-\int \frac{2}{x+2} \cdot d x$
$\Rightarrow \int d x-2 \int \frac{d x}{x+2}$
$\Rightarrow x-2 \ln |x+2|+c 1$
$\therefore l1=x-2 \ln |x+2|+c 1$
For 12
$\Rightarrow \int \frac{\sqrt{x+1}}{x+2} d x$
Assume $x+1=t$
$d t=d x$
$\Rightarrow \int \frac{\sqrt{t}}{t+1} d t$
Substitute $u=\sqrt{t}$
$\mathrm{dt}=2 \sqrt{\mathrm{t}} \cdot \mathrm{d} \mathrm{u}$
$t=u^{2}$
$\Rightarrow 2 \int \frac{\mathrm{u}^{2}}{\mathrm{u}^{2}+1} \mathrm{du}$
Add and subtract 1 in the above equation:
$\Rightarrow 2 \int \frac{u^{2}+1-1}{u^{2}+1} d u$
$\Rightarrow 2 \int \frac{u^{2}+1}{u^{2}+1} d u-\int \frac{1}{u^{2}+1} d u$
$\Rightarrow 2 \int d u-\int \frac{1}{u^{2}+1} d u$
$\Rightarrow 2 u-\tan ^{-1}(u)+c 2$
But $u=\sqrt{t}$
$\therefore 2 \sqrt{t}-\tan ^{-1}(\sqrt{t})+c 2$
Also $t=x+1$
$\therefore 2 \sqrt{(} x+1)-\tan ^{-1}(x+1)+c 2$
$l=11+12$
$\therefore 1=x-2 \ln |x+2|+c 1+2 \sqrt{(} x+1)-\tan ^{-1}(x+1)+c 2$
$l=x-2 \ln |x+2|+2 \sqrt{(} x+1)-\tan ^{-1}(x+1)+c$