Nghiệm của phương trình \( \cos \left( {x - \dfrac{ \pi }{3}} \right) - \sqrt 3 \sin \left( {x - \dfrac{ \pi }{3}} \right) = 1 \) là.
Giải chi tiết:
TXĐ: \(D = \mathbb{R}\).
\(\begin{array}{l}\,\,\,\,\,\,\cos \left( {x - \dfrac{\pi }{3}} \right) - \sqrt 3 \sin \left( {x - \dfrac{\pi }{3}} \right) = 1\\ \Leftrightarrow \dfrac{1}{2}.\cos \left( {x - \dfrac{\pi }{3}} \right) - \dfrac{{\sqrt 3 }}{2}\sin \left( {x - \dfrac{\pi }{3}} \right) = \dfrac{1}{2}\\ \Leftrightarrow \cos \dfrac{\pi }{3}.\cos \left( {x - \dfrac{\pi }{3}} \right) - \sin \dfrac{\pi }{3}.\sin \left( {x - \dfrac{\pi }{3}} \right) = \dfrac{1}{2}\\ \Leftrightarrow \cos \left( {x - \dfrac{\pi }{3} + \dfrac{\pi }{3}} \right) = \cos \dfrac{\pi }{3}\\ \Leftrightarrow \cos x = \cos \dfrac{\pi }{3} \Leftrightarrow x = \pm \dfrac{\pi }{3} + k2\pi \,\,\left( {k \in \mathbb{Z}} \right)\end{array}\)
Chọn A.