Giải phương trình \(\cos 5x.\cos x = cos4x.\)
A.\(x = \frac{{k\pi }}{5}\,\,\,\left( {k \in Z} \right).\)
B.\(x = \frac{{k\pi }}{3}\,\,\,\left( {k \in Z} \right).\)
C. \(x = k\pi \,\,\,\left( {k \in Z} \right).\)
D. \(x = \frac{{k\pi }}{7}\,\,\,\left( {k \in Z} \right).\)
A.\(x = \frac{{k\pi }}{5}\,\,\,\left( {k \in Z} \right).\)
B.\(x = \frac{{k\pi }}{3}\,\,\,\left( {k \in Z} \right).\)
C. \(x = k\pi \,\,\,\left( {k \in Z} \right).\)
D. \(x = \frac{{k\pi }}{7}\,\,\,\left( {k \in Z} \right).\)
Loga
Hóa Học lớp 12
