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JEE Mains · Maths · STD 11 - 3. trignometrical ratios,functions and identities

The sum of the solutions \(x \in \mathbb{R}\) of the equation \(\frac{3 \cos 2 x+\cos ^3 2 x}{\cos ^6 x-\sin ^6 x}=x^3-x^2+6\) is

  1. A \(0\)
  2. B \(1\)
  3. C \(-1\)
  4. D \(3\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(-1\)

Step-by-step Solution

Detailed explanation

\( \frac{3 \cos 2 x+\cos ^3 2 x}{\cos ^6 x-\sin ^6 x}=x^3-x^2+6 \) \( \Rightarrow \frac{\cos 2 x\left(3+\cos ^2 2 x\right)}{\cos 2 x\left(1-\sin ^2 x \cos ^2 x\right)}=x^3-x^2+6 \) \( \Rightarrow \frac{4\left(3+\cos ^2 2 x\right)}{\left(4-\sin ^2 2 x\right)}=x^3-x^2+6 \)…