Đáp án:
\(D=R\)\$ \left \{ \dfrac{3\pi}{5}+k.\pi , k \epsilon Z\right \}$
Giải thích các bước giải:
\(\tan (x-\dfrac{\pi}{10})=\dfrac{\sin (x-\dfrac{\pi}{10})}{\cos (x-\dfrac{\pi}{10})}\)
ĐK: \(\cos (x-\dfrac{\pi}{10}) \neq 0\)
\(\Leftrightarrow x-\dfrac{\pi}{10} \neq \dfrac{\pi}{2}+ k.\pi\) \(k \epsilon Z\)
\(\Leftrightarrow x \neq \dfrac{3\pi}{5}+k.\pi\)
\(D=R\)\$ \left \{ \dfrac{3\pi}{5}+k.\pi , k \epsilon Z\right \}$
