Question

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

• A. -8
• B. 7
• C. 3
• D. 5

Answer 1

The correct option is A -8

Step 1:- If one root of the equation $2x^2+ax+6=0$ is 3, then substitute $x=3$ in the equation,

Step 2:- $2(3{)}^2+3a+6=0$
$\Rightarrow 18+3a+6=0$

Step 3:- $24+3a=0$
$\Rightarrow a=-8$