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KCET · Maths · Indefinite Integration

\( \int \frac{1}{\sqrt{3-6 x-9 x^{2}}} d x \) is equal to

  1. A \( \sin ^{-1}\left(\frac{3 x+1}{2}\right)+C \)
  2. B \( \sin ^{-1}\left(\frac{3 x+1}{6}\right)+C \)
  3. C \( \frac{1}{3} \sin ^{-1}\left(\frac{3 x+1}{2}\right)+C \)
  4. D \( \sin ^{-1}\left(\frac{2 x+1}{3}\right)+C \)
Verified Solution

Answer & Solution

Correct Answer

(C) \( \frac{1}{3} \sin ^{-1}\left(\frac{3 x+1}{2}\right)+C \)

Step-by-step Solution

Detailed explanation

Given that, \( \int \frac{1}{\sqrt{3-6 x-9 x^{2}}} d x \)
Since, \( 3-6 x-9 x^{2}=4-(3 x+1)^{2} \)
So, \( \int \frac{1}{\sqrt{4-(3 x+1)^{2}}} d x \) \( =\frac{1}{3} \sin ^{-1}\left(\frac{3 x+1}{2}\right)+c \)