Practicing Success
$\int\left\{\sin \left(\log _e x\right)+\cos \left(\log _e x\right)\right\} d x$ is equal to |
$\sin \left(\log _e x\right)+\cos \left(\log _e x\right)+C$ $x \sin \left(\log _e x\right)+C$ $x \cos \left(\log _e x\right)+C$ none of these |
$x \sin \left(\log _e x\right)+C$ |
We have, $I =\int\left\{\sin \left(\log _e x\right)+\cos \left(\log _e x\right)\right\} d x$ $\Rightarrow I =\int e^t(\sin t+\cos t) d t$, where $t=\log _e x$ $\Rightarrow I=e^t \sin t+C~~~~~\left[∵ \int e^x\left\{f(x)+f'(x)\right\} d x=e^x f(x)+C\right] $ $\Rightarrow I=x \sin \left(\log _e x\right)+C$ |