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QJEEM24Ma8f0f: JEE Main 2024 Mathematics - Class 12 JEEM24Ma8f0f Solution: Let , where is the constant of integration. Then is equal to :

Let ∫2−tan⁡x3+tan⁡x dx=12(αx+log⁡e∣βsin⁡x+γcos⁡x∣)+C\int \frac{2-\tan x}{3+\tan x} \mathrm{~d} x=\frac{1}{2}\left(\alpha x+\log _e|\beta \sin x+\gamma \cos x|\right)+C , where CC is the constant of integration. Then α+γβ\alpha+\frac{\gamma}{\beta} is equal to :

Multiple Choice Options

  • A 3
  • B 7
  • C 1
  • D 4

Step-by-Step Verified Solution

I=∫2−tan⁡x3+tan⁡xdx=∫2cos⁡x−sin⁡x3cos⁡x+sin⁡xdxI=\int \frac{2-\tan x}{3+\tan x} d x=\int \frac{2 \cos x-\sin x}{3 \cos x+\sin x} d x

Put, 2cos⁡x−sin⁡x=a(−3sin⁡x+cos⁡x)+b(3cos⁡x+sin⁡x)2 \cos x-\sin x=a(-3 \sin x+\cos x)+ b(3 \cos x+\sin x)

amp;a+3b=2.... (i)amp;−3a+b=−1.... (ii)\begin{aligned}& a+3 b=2 \quad \text{.... (i)}\\& -3 a+b=-1 \quad \text{.... (ii)}\end{aligned}

From equation (i) and (ii) a=b=12a=b=\frac{1}{2}

I=12∫−3sin⁡x+cos⁡x3cos⁡x+sin⁡xdx+12∫3cos⁡x+sin⁡x3cos⁡x+sin⁡xdxI=\frac{1}{2} \int \frac{-3 \sin x+\cos x}{3 \cos x+\sin x} d x+\frac{1}{2} \int \frac{3 \cos x+\sin x}{3 \cos x+\sin x} d x

I=12ln⁡∣3cos⁡x+sin⁡x∣+12x=12(dx+log⁡∣βsin⁡x+γcos⁡x∣)I=\frac{1}{2} \ln |3 \cos x+\sin x|+\frac{1}{2} x= \frac{1}{2}(d x+\log |\beta \sin x+\gamma \cos x|)

On comparing, we get

I=12ln⁡∣3cos⁡x+sin⁡x∣+12x=12(dx+log⁡∣βsin⁡x+γcos⁡x∣)I=\frac{1}{2} \ln |3 \cos x+\sin x|+\frac{1}{2} x=\frac{1}{2}(d x+\log |\beta \sin x+\gamma \cos x|)

On comparing, we get

amp;⇒12(x+log⁡(∣3cos⁡x+sin⁡x∣))=amp;12(dx+log⁡∣βsin⁡x+γcos⁡x∣)\begin{aligned}& \Rightarrow \frac{1}{2}(x+\log (|3 \cos x+\sin x|))= \\& \qquad \frac{1}{2}(d x+\log |\beta \sin x+\gamma \cos x|)\end{aligned}

amp;α=1,β=1,γ=3amp;α+γβ=1+31=4\begin{aligned}& \alpha=1, \beta=1, \gamma=3 \\& \alpha+\frac{\gamma}{\beta}=1+\frac{3}{1}=4\end{aligned}

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