Đáp án:
1.
a . TXĐ: \(D=R\)\{\(k.2\pi\)} \((k \epsilon Z)\)
b. TXĐ: \(D=R\)\{\(\dfrac{\pi}{4}+k.\dfrac{\pi}{2};\dfrac{\pi}{2}+k.\pi\)} \((k \epsilon Z)\)
Giải thích các bước giải:
1.
a. ĐK: \(\cos x-1 \neq 0\)
\(\Leftrightarrow \cos x \neq 1\)
\(\Leftrightarrow x \neq k.2\pi\)
TXĐ: \(D=R\)\{\(k.2\pi\)} \((k \epsilon Z)\)
b.
\(\tan 2x+\tan x+1=\dfrac{\sin 2x}{\cos 2x}+\dfrac{\sin x}{\cos x}+1\)
ĐK:
$\begin{cases}\cos 2x \neq 0\\ \cos x \neq 0\end{cases}$
\(\Leftrightarrow \) $\begin{cases}2x \neq \dfrac{\pi}{2}+k.\pi\\ x \neq \dfrac{\pi}{2}+k.\pi\end{cases}$
\(\Leftrightarrow \) $\begin{cases}x \neq \dfrac{\pi}{4}+k.\dfrac{\pi}{2}\\ x \neq \dfrac{\pi}{2}+k.\pi\end{cases}$
TXĐ: \(D=R\)\{\(\dfrac{\pi}{4}+k.\dfrac{\pi}{2};\dfrac{\pi}{2}+k.\pi\)}
