A. \(\cos 2x.4{\cos ^2}x + \frac{1}{{{{\sin }^2}\frac{1}{{{x^2}}}}} - \cos 2x.4{\sin ^3}x\)
B. \(2\cos 4x + \frac{2}{{{x^3}.{{\sin }^2}\frac{1}{{{x^2}}}}}\)
C. \(2\cos 4x + \frac{2}{{x.{{\sin }^2}\frac{1}{{{x^2}}}}}\)
D. \(2\cos 4x - \frac{2}{{{x^3}.{{\sin }^2}\frac{1}{{{x^2}}}}}\)
D
\(y = \sin 2x\left( {{{\cos }^4}x - {{\sin }^4}x} \right) - \cot \frac{1}{{{x^2}}} \Rightarrow y' = \frac{4}{2}\cos 4x + \frac{1}{{{{\sin }^2}\frac{1}{{{x^2}}}}}.\left( {\frac{1}{{{x^2}}}} \right)' = 2\cos 4x - \frac{2}{{{x^3}.{{\sin }^2}\frac{1}{{{x^2}}}}}\)
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