Question

tan (x-30 độ ) nhân cos ( 2x -150 độ )=0

Answer 1

ĐKXĐ: \(cos\left(x-30^0\right)\ne0\Leftrightarrow x\ne120^0+k180^0\)

\(tan\left(x-30^0\right)cos\left(2x-150^0\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}tan\left(x-30^0\right)=0\\cos\left(2x-150^0\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x-30^0=k180^0\\2x-150^0=90^0+k180^0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=30^0+k180^0\\x=120^0+k90^0\end{matrix}\right.\)

\(\Rightarrow x=30^0+k180^0\)