$\int \frac{\sin x+8 \cos x}{4 \sin x+6 \cos x} d x$ is equal to

$\int \frac{\sin x+8 \cos x}{4 \sin x+6 \cos x} d x$ is equal to
  1. $x+\frac{1}{2} \log (4 \sin x+6 \cos x)+c$
  2. $2 x+\log (2 \sin x+3 \cos x)+c$
  3. $x+2 \log (2 \sin x+3 \cos x)+c$
  4. $\frac{1}{2} \log (4 \sin x+6 \cos x)+c$

Solution

\(\int \frac{\sin x+8 \cos x}{4 \sin x+6 \cos x} d x\) Write numerator as: \(\sin x+8 \cos x=\frac{1}{2}(4 \cos x-6 \sin x)+(4 \sin x+6 \cos x)\) So, \(\begin{gathered} \int \frac{4 \sin x+6 \cos x}{4 \sin x+6 \cos x} d x+\frac{1}{2} \int \frac{4 \cos x-6 \sin x}{4 \sin x+6 \cos x} d x \\ =\int d x+\frac{1}{2} \int \frac{d(4 \sin x+6 \cos x)}{4 \sin x+6 \cos x} \\ =x+\frac{1}{2} \log (4 \sin x+6 \cos x)+C \end{gathered}\)

Asked in: MHT CET Full Test 13

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