Question

If $4$ is a root of the quadratic equation $x^2+mx–2=0$, then the value of $m$ is

• A. $\frac{9}{2}$
  
• B. $\frac{11}{2}$
  
• C. $\frac{-7}{2}$
  
• D. $\frac{-5}{2}$
  

Answer 1

The correct option is C $\frac{-7}{2}$


The given quadratic equation is $x^2+mx–2=0$.
Now, $4$ is the root of the given quadratic equation.
$\therefore (4{)}^2+4m-2=0$
$\Rightarrow 16+4m-2=0$
$\Rightarrow 14+4m=0$
$\Rightarrow 4m=-14$
$\Rightarrow m=\frac{-14}{4}$
$\Rightarrow m=\frac{-7}{2}$
Hence, the correct answer is option (3).