Giải các phương trình sau

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1. \( 2\cos 4x + \sqrt{3} = 0 \)
2. \( -2\cos x + \sqrt{2} = 0 \)
3. \( \cos \left( 3x - \frac{\pi}{5} \right) + 1 = 0 \)
4. \( 2\cos \left( 5x + \frac{\pi}{3} \right) - 1 = 0 \)
5. \( \cos 10x = 0 \)
6. \( \cos \left( 8x + \frac{\pi}{4} \right) = \frac{\sqrt{3}}{2} \)
7. \( \cos 3x = \cos 2x \)
8. \( 2\cos \left( 6x - \frac{\pi}{2} \right) - \sqrt{3} = 0 \)
9. \( \cos 5x - \cos \left( 2x - \frac{\pi}{6} \right) = 0 \)
10. \( \cos \left( 2x + \frac{\pi}{3} \right) = -1 \)