[tex]\displaystyle\bf\\3x^2-x-2=0\\\\x_{12}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}=\frac{1\pm\sqrt{1-4\times3\times(-2)}}{2\times3}=\\\\=\frac{1\pm\sqrt{1+24}}{6}=\frac{1\pm\sqrt{25}}{6}=\frac{1\pm5}{6}\\\\x_1=\frac{1-5}{6}=\frac{-4}{6}=-\frac{2}{3}\\\\x_1=\frac{1+5}{6}=\frac{6}{6}=1[/tex]
