Question

If $r=3$ is a root of quadratic equation $k{r}^2-kr-3=0$, then value of $k$ is :

• A. $\frac{1}{2}$
• B. $2$
• C. $-2$
• D. $-\frac{1}{2}$

Answer 1

Answer: (A)

$\frac{1}{2}$

Given quadratic equation is $k{r}^2-kr-3=0$ and $r=3$ is the root of this equation

As $r=3$ is the root of the equation then,

$k(3{)}^2-k(3)-3=0$ should be satisfied,

i.e., $9k-3k-3=0$

$\Rightarrow 6k=3$

or, $k=\frac{1}{2}$