\[x^{2} - 7x - 3 = 0\ \]
\[x_{1} + x_{2} = 7;\ \]
\[x_{1} \cdot x_{2} = - 3\]
\[\frac{1}{x_{1}} + \frac{1}{x_{2}} = \frac{x_{2} + x_{1}}{x_{1}x_{2}} = \frac{7}{- 3} = - 2\frac{1}{3}\]