\(3{\cos ^4}x - 4{\sin ^2}x{\cos ^2}x + {\sin ^4}x...

Câu hỏi: \(3{\cos ^4}x - 4{\sin ^2}x{\cos ^2}x + {\sin ^4}x = 0.\)

A \(\left[ \begin{array}{l}x = \frac{{2\pi }}{3} + k2\pi \\x = \frac{\pi }{3} + k2\pi \\x = \frac{\pi }{4} + k2\pi \\x = \frac{{3\pi }}{4} + k2\pi \end{array} \right.\,\,\,\,\left( {k \in \mathbb{Z}} \right)\)

B \(\left[ \begin{array}{l}
x = \frac{{2\pi }}{3} + k\pi \\
x = \frac{\pi }{4} + k\pi
\end{array} \right.\)

C \(\left[ \begin{array}{l}x = \frac{{2\pi }}{3} + k2\pi \\x = \frac{\pi }{3} + k2\pi \\x =  - \frac{\pi }{4} + k2\pi \\x = \frac{{5\pi }}{4} + k2\pi \end{array} \right.\,\,\,\,\left( {k \in \mathbb{Z}} \right)\)

D \(\left[ \begin{array}{l}x = \frac{{2\pi }}{3} + k\pi \\x = \frac{\pi }{3} + k\pi \\x = \frac{\pi }{4} + k\pi \\x = \frac{{3\pi }}{4} + k\pi \end{array} \right.\,\,\,\,\left( {k \in \mathbb{Z}} \right)\)