Giải phương trình: \(\cos 2x + 9\cos x + 5 = 0\).
A.\(S = \left\{ { \pm \dfrac{{2\pi }}{3} + k\pi } \right\}.\)
B.\(S = \left\{ { \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
C.\(S = \left\{ { \pm \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
D.\(S = \left\{ {- \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
A.\(S = \left\{ { \pm \dfrac{{2\pi }}{3} + k\pi } \right\}.\)
B.\(S = \left\{ { \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
C.\(S = \left\{ { \pm \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
D.\(S = \left\{ {- \dfrac{{2\pi }}{3} + k2\pi } \right\}.\)
Loga
Hóa Học lớp 12
