Nghiệm phương trình $2{{\cos }^{2}}x-3\cos x+1=0$ là
A.$\left[ \begin{align} & x=k\pi \\ & x=\pm \dfrac{\pi }{3}+k2\pi \\ \end{align} \right.\,$
B.$\left[ \begin{align} & x=k2\pi \\ & x=\pm \dfrac{\pi }{3}+k2\pi \\ \end{align} \right.\,$
C.$\left[ \begin{align} & x=\dfrac{\pi }{2}+k\pi \\ & x=\pm \dfrac{\pi }{4}+k2\pi \\ \end{align} \right.\,$
D.$\left[ \begin{align} & x=\dfrac{\pi }{2}+k2\pi \\ & x=\pm \dfrac{\pi }{4}+k2\pi \\ \end{align} \right.\,$
A.$\left[ \begin{align} & x=k\pi \\ & x=\pm \dfrac{\pi }{3}+k2\pi \\ \end{align} \right.\,$
B.$\left[ \begin{align} & x=k2\pi \\ & x=\pm \dfrac{\pi }{3}+k2\pi \\ \end{align} \right.\,$
C.$\left[ \begin{align} & x=\dfrac{\pi }{2}+k\pi \\ & x=\pm \dfrac{\pi }{4}+k2\pi \\ \end{align} \right.\,$
D.$\left[ \begin{align} & x=\dfrac{\pi }{2}+k2\pi \\ & x=\pm \dfrac{\pi }{4}+k2\pi \\ \end{align} \right.\,$
Loga
Hóa Học lớp 12
