Question

If one root of the equation $2x^2+ax+6=0$ is 2, then a = ?
(a) 7
(b) −7
(c) $\frac{7}{2}$
(d) $\frac{-7}{2}$

Answer 1

(b) −7
$$\begin{gathered} \text{It is given that one root of the equation 2}{x}^2\text{+}ax+6=0\text{is 2.} \\ \therefore \text{2}\times {\text{2}}^2\text{+}a\times 2+6=0 \\ \Rightarrow 2a+14=0 \\ \Rightarrow a=-7 \end{gathered}$$