`a) 2cos (x/2) + sqrt{3} = 0`
`<=> 2cos (x/2) = -sqrt{3}`
`<=> cos (x/2) = -(\sqrt{3})/2`
`<=> cos (x/2) = cos ((5π)/6)`
`<=>` \(\left[ \begin{array}{l}\frac{x}{2} = \frac{5π}{6} + k2π\\\frac{x}{2} = -\frac{5π}{6} + k2π\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = \frac{5π}{3} + k4π\\x = \frac{-5π}{3} + k4π\end{array} \right.\) `(k ∈ ZZ)`
`e) sin 2x(2sin x - sqrt{2}) = 0`
`<=>` \(\left[ \begin{array}{l}sin 2x = 0\\2sin x - \sqrt{2} = 0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}2x = kπ\\sin x = \frac{\sqrt{2}}{2} \end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = k\frac{π}{2}\\x = \frac{π}{4} + k2π\\x = \frac{3π}{4} + k2π\end{array} \right.\) `(k ∈ ZZ)`
