General solution of the differential equation $x \cos y \mathrm{~d} y=\left(x \mathrm{e}^x \log…

General solution of the differential equation $x \cos y \mathrm{~d} y=\left(x \mathrm{e}^x \log x+\mathrm{e}^x\right) \mathrm{d} x$ is (where $C$ is a constant of integration.)
  1. $\sin y=\mathrm{e}^x \log x+C$
  2. $\sin y=\mathrm{e}^x+C \log x$
  3. $\sin y=C \mathrm{e}^x+\log x$
  4. $\mathrm{e}^x \sin y=\log x+C$

Solution

$\begin{aligned} & x \cos y \mathrm{~d} y=\left(x \mathrm{e}^x \log x+\mathrm{e}^x\right) \mathrm{d} x \\ & \Rightarrow \int \cos y \mathrm{~d} y=\int \mathrm{e}^x\left\{\log x+\frac{1}{x}\right\} \mathrm{d} x \\ & \Rightarrow \sin y=\mathrm{e}^x \log x+C\left[\because \int \mathrm{e}^x\left\{f(x)+f^{\prime}(x)\right\} \mathrm{d} x=\mathrm{e}^x f(x)+C\right]\end{aligned}$

Asked in: MHT CET 2022 (08 Aug Shift 2)

Practice more Differential Equations questions on Aicharya