$$B=(7\nu-3)(3\nu$$
$B=3\nu \left(7\nu -3\right)$
$\nu =\frac{\sqrt{84B+81}}{42}+\frac{3}{14}$
$\nu =-\frac{\sqrt{84B+81}}{42}+\frac{3}{14}\text{, }B\geq -\frac{27}{28}$
