For $2x^2 - 9x + 4 = 0$, we have $a = 2$, $b = -9$, $c = 4$.
$$\text{Sum of roots} = \frac{-b}{a} = \frac{-(-9)}{2} = \frac{9}{2}$$
$$\text{Product of roots} = \frac{c}{a} = \frac{4}{2} = 2$$
Source: Chapter 4, Quadratic Equations
Examiners expect you to identify $a$, $b$, $c$ and directly apply the two formulae: sum $= -b/a$ and product $= c/a$. These follow from the quadratic formula — if $\alpha$ and $\beta$ are roots, then $\alpha + \beta = -b/a$ and $\alpha\beta = c/a$. No need to actually find the roots. Show the substitution step clearly for full marks.