Toán Lớp 11: giải ptlg cơ bản:cos(x-2pi/5)=cos2x
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 11: giải ptlg cơ bản:cos(x-2pi/5)=cos2x
Comments ( 2 )
\cos (x – \frac{{2\pi }}{5}) = \cos 2x\\
\Rightarrow \{ \begin{array}{*{20}{c}}
{x – \frac{{2\pi }}{5} = 2x + k2\pi }\\
{x – \frac{{2\pi }}{5} = – 2x + k2\pi }
\end{array}\\
\Rightarrow \{ \begin{array}{*{20}{c}}
{x = – \frac{{2\pi }}{5} – k2\pi }\\
{x = \frac{{2\pi }}{{15}} + \frac{{k2\pi }}{3}}
\end{array}
\end{array}\]