Question:
If one root of the equation $2 x^{2}+a x+6=0$ is 2 , then $a=?$
(a) 7
(b) $-7$
(c) $\frac{7}{2}$
(d) $\frac{-7}{2}$
Solution:
(b) −7
It is given that one root of the equation $2 x^{2}+a x+6=0$ is 2 .
$\therefore 2 \times 2^{2}+a \times 2+6=0$
$\Rightarrow 2 a+14=0$
$\Rightarrow a=-7$