`a) 3cot² x - 2cot x - 1 = 0`
`<=>` \(\left[ \begin{array}{l}cot x = 1\\cot x = -\dfrac{1}{3}\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = \dfrac{\pi}{4} + kπ\\x = arccot \dfrac{-1}{3} + kπ\end{array} \right.\) `(k ∈ ZZ)`
`b) sin x + cos x = 1`
`<=> sqrt{2}sin (x + π/4) = 1`
`<=> sin (x + π/4) = sin (π/4)`
`<=>` \(\left[ \begin{array}{l}x = k2π\\x = \dfrac{π}{2} + k2π\end{array} \right.\) `(k ∈ ZZ)`
