Question

\(2sinx.sin3x+\left(3\sqrt{2}-1\right)cos2x-3=0\)

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Answer 1

\(\Leftrightarrow cos2x-cos4x+\left(3\sqrt{2}-1\right)cos2x-3=0\)

\(\Leftrightarrow-cos4x+3\sqrt{2}cos2x-3=0\)

\(\Leftrightarrow-2cos^22x+3\sqrt{2}cos2x-2=0\)

\(\Leftrightarrow\left[{}\begin{matrix}cos2x=\sqrt{2}\left(loại\right)\\cos2x=\dfrac{\sqrt{2}}{2}\end{matrix}\right.\)

\(\Leftrightarrow...\)