Question

For what value of k, the quadratic equation
$x^2-kx+9=0$ has equals roots

Answer 1

The given equation is

$x^2-kx+9=0$ ... (1)

where a = 1

b = -k

c = a

since the equation (1) has equal roots

$\Rightarrow b^2-4ac=0$

$\Rightarrow (-k{)}^2-4(1\left)\right(9)=0$

$\Rightarrow (k{)}^2-36=0$

$\Rightarrow k^2=36$

$\Rightarrow k=\pm 6$

Hence volume of k=6, -6.