Реши уравнения

\(x^2 + 3x - 3 = 0\) ,

\(D = b^2 - 4ac = 9 - 4 \cdot 1 \cdot (-3) = 21\) ;

\(x\_1=\cfrac{-b+\sqrt{D}}{2a}=\cfrac{-3+\sqrt{21}}{2}\) ,

\(x\_2=\cfrac{-b-\sqrt{D}}{2a}=\cfrac{-3-\sqrt{21}}{2}\) .

Ответ: \(\cfrac{-3+\sqrt{21}}{2}\) , \(\cfrac{-3-\sqrt{21}}{2}\) .

а) \(2x^2 - x - 2 = 0\) ;

б) \(3x^2 - 3x - 1 = 0\) ;

в) \(-2x^2 + x + 5 = 0\) .