Question

If the following quadratic equation has two equal and real roots then find the value of $k$ :
$x^2-kx+25=0$

Answer 1

For equal & real roots, discriminant of quadratic equation has to be zero.

$D=0$

$D=k^2-4\left(25\right)=0$

$\Rightarrow (k{)}^2-(100)=0$

$\Rightarrow k^2=100$

$\Rightarrow k=10,-10$