$$5 { m }^{ 2 } +2m+K=0$$
$K=-m\left(5m+2\right)$
$m=\frac{\sqrt{1-5K}-1}{5}$
$m=\frac{-\sqrt{1-5K}-1}{5}$
$m=\frac{\sqrt{1-5K}-1}{5}$
$m=\frac{-\sqrt{1-5K}-1}{5}\text{, }K\leq \frac{1}{5}$
