Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

\(\int e^{x}\sin x dx\) equals

Options:

\(e^{x}\left(\sin x-\cos x\right)+C\)

\(e^{x} \sin x+\cos x+C\)

\(\sin x-e^{x}\cos x+C\)

\(\frac{e^{x}}{2}\left(\sin x-\cos x\right)+C\)

Correct Answer:

\(\frac{e^{x}}{2}\left(\sin x-\cos x\right)+C\)

Explanation:

Integrating by parts

I = \(\int e^{x}\sin x dx\)

   = \(e^x\int sinx. dx − \int \left(\frac{d}{dx}e^x\right). \int sinx .dx\)

   = \(e^x(− cosx) + \int e^x cosx. dx\)

I = \(− e^x. cosx + e^x. sinx − \int e^x sinx .dx\)

⇒ I = \(e^x (sinx − cosx) − I\)

⇒ 2I = \(e^x (sinx − cosx)\)

⇒ I = \(\frac{e^x}{2} (sinx − cosx) + c\)