1 câu trả lời
$\tan 4x$
Đk: \(\cos 4x\ne 0\Leftrightarrow 4x\ne \dfrac{\pi}{2}+k\pi\)
\(\Leftrightarrow x\ne\dfrac{\pi}{8}+k\dfrac{\pi}{4}\)
Phương trình \(\Rightarrow 4x=\arctan 4+k\pi\)
\(\Rightarrow x=\dfrac{\arctan4}{4}+k\dfrac{\pi}{4}\).
$\tan 4x$
Đk: \(\cos 4x\ne 0\Leftrightarrow 4x\ne \dfrac{\pi}{2}+k\pi\)
\(\Leftrightarrow x\ne\dfrac{\pi}{8}+k\dfrac{\pi}{4}\)
Phương trình \(\Rightarrow 4x=\arctan 4+k\pi\)
\(\Rightarrow x=\dfrac{\arctan4}{4}+k\dfrac{\pi}{4}\).
