\[y = 2x^{2} - x - 15\]
\[y = 0:\]
\[2x^{2} - x - 15 = 0\]
\[D = 1 + 120 = 121\]
\[x_{1} = \frac{1 + 11}{4} = 3;\ \ \ \ \]
\[x_{2} = \frac{1 - 11}{4} = - \frac{10}{4} = - 2,5\]
\[Координаты\ точек\ \]
\[пересечения\ с\ осью\ x:\ \ \]
\[(3;0);\ \ ( - 2,5;0).\]
\[y = - 3x^{2} + 5x + 28\]
\[y = 0:\]
\[- 3x^{2} + 5x + 28 = 0\]
\[3x^{2} - 5x - 28 = 0\]
\[D = 25 + 336 = 361\]
\[x_{1} = \frac{5 + 19}{6} = \frac{24}{6} = 4;\ \ \ \]
\[x_{2} = \frac{5 - 19}{6} = - \frac{14}{6} = - \frac{7}{3} =\]
\[= - 2\frac{1}{3}\]
\[Координаты\ точек\ \]
\[пересечения\ с\ осью\ x:\]
\[(4;0);\ \ \left( - 2\frac{1}{3};0 \right).\]