Question
Integrate the function: $\frac{{2\cos x - 3\sin x}}{{6\cos x + 4\sin x}}$

Answer

Let $I = \int {\frac{{2\cos x - 3\sin x}}{{6\cos x + 4\sin x}}dx} $

$ = \int {\frac{{2\cos x - 3\sin x}}{{2\left( {2\sin x + 3\cos x} \right)}}dx} $

$= \frac{1}{2}\int {\frac{{2\cos x - 3\sin x}}{{2\sin x + 3\cos x}}dx} $…(i)

Putting 2 sin x + 3 cos x = t

$ \Rightarrow 2\cos x - 3\sin x = \frac{{dt}}{{dx}}$

$ \Rightarrow $ (2 cos x - 3 sin x)dx = dt

$\therefore$ From eq. (i), $I = \frac{1}{2}\int {\frac{{dt}}{t} = \frac{1}{2}\log \left| t \right| + c} $

$= \frac{1}{2}\log \left| {2\sin x + 3\cos x} \right| + c$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free