$a=-\frac{b}{1-b}\text{, }b=\frac{-\sqrt{c\left(c-4\right)}+c}{2}\text{, }c\neq 0$
$a=-\frac{b}{1-b}\text{, }b=\frac{\sqrt{c\left(c-4\right)}+c}{2}\text{, }c\neq 0$

$a=-\frac{b}{1-b}\text{, }b=\frac{-\sqrt{c(c-4)}+c}{2}\text{, }c\in (-\infty,0)\cup [4,\infty)\text{; }a=-\frac{b}{1-b}\text{, }b=\frac{\sqrt{c(c-4)}+c}{2}\text{, }c\in (-\infty,0)\cup [4,\infty)$