$\int[\sin |\log x|+\cos |\log x|] d x=$

$\int[\sin |\log x|+\cos |\log x|] d x=$
  1. $\sin |\log x|+c$
  2. $\cos |\log x|+c$
  3. $x \cos |\log x|+c$
  4. $x \sin |\log x|+c$

Solution

Let $\mathrm{I}=\int[\sin |\log \mathrm{x}|+\cos |\log \mathrm{x}|] \mathrm{dx}$ Put $\log \mathrm{x}=\mathrm{t} \Rightarrow \frac{1}{\mathrm{x}} \mathrm{dx}=\mathrm{dt} \Rightarrow \mathrm{dx}=\mathrm{e}^{\mathrm{t}} \mathrm{dt}$ $\begin{aligned} & \therefore \mathrm{I}=\int(\sin +\cos t) \mathrm{e}^{\mathrm{t}} d t \\ & =\int \mathrm{e}^{\mathrm{t}}(\sin \mathrm{t}+\cos t) d t=\mathrm{e}^{\mathrm{t}} \sin \mathrm{t}+\mathrm{c}=\mathrm{x} \sin |\log \mathrm{x}|+\mathrm{c} \end{aligned}$

Asked in: MHT CET 2021 (21 Sep Shift 2)

Practice more Indefinite Integration questions on Aicharya