VTMO 2019 — Grade 9 — semifinal Question 18

A line through $\left(2 , 0\right)$ meets $y = ax^{2} , a \ne 0$ at two distinct points with abscissas $x _{1} , x _{2}$. Find $\frac{1}{x} _{1} + \frac{1}{x} _{2}$.