[tex]3 {x}^{2} - 2x - 1 = 0 \\ d = {( - 2)}^{2} - 4 \times 3 \times ( - 1) = 4 + 12 = 16 \\ x = \frac{2 + \sqrt{16} }{6} = \frac{2 + 4}{6} = 1 \\ x = \frac{2 - \sqrt{16} }{6} = \frac{2 - 4}{6} = - \frac{1}{3} \\ x \times x = - \frac{1}{3} \times 1 = - \frac{1}{3} \\ x + x = - \frac{1}{3} + 1 = \frac{2}{3} [/tex]