Question

Find the values of $k$ for which the quadratic equation $4x^2+5Kx+25=0$ has equal roots.

Answer 1

For equal roots, $D=b^2-4ac=0$

$where,a=4,b=5k$ and $c=25$

$\Rightarrow (5k{)}^2-4(4\left)\right(25)=0$

$\Rightarrow 25k^2-25\left(16\right)=0$

$\Rightarrow k^2=16$

$\Rightarrow k=\pm 4$.