Question

If one root of the equation $2x^2+ax+6=0$ is 3, then the value of a is ___________.

• A. -8
• B. 7
• C. 3
• D. 5

Answer 1

The correct option is A

-8

If one root of the equation $2x^2+ax+6=0$ is 3, then substituting $x=3$ will satisfy the equation.

$2(3{)}^2+3a+6=0$

$\Rightarrow 18+3a+6=0$

$\Rightarrow 24+3a=0$

$\Rightarrow a=-8$