Câu 2:
a: ĐKXĐ: \(2x-\dfrac{pi}{3}< >\dfrac{pi}{2}+kpi\)
=>\(x< >\dfrac{5}{12}pi+\dfrac{kpi}{2}\)
\(PT\Leftrightarrow2x-\dfrac{pi}{3}=\dfrac{pi}{6}+kpi\)
=>2x=pi/2+kpi
=>x=pi/4+kpi/2
b: \(\Leftrightarrow\left[{}\begin{matrix}45^0-x=45^0+k\cdot360^0\\45^0-x=135^0+k\cdot360^0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-k\cdot360^0\\x=-90^0-k\cdot360^0\end{matrix}\right.\)
c: \(\Leftrightarrow sin3x=sin\left(-x\right)\)
=>3x=-x+k2pi hoặc 3x=pi+x+k2pi
=>4x=k2pi hoặc 2x=pi+k2pi
=>x=kpi/2 hoặc x=pi/2+kpi
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