$$ax^2+bx-c=0~~~~;~~~~x=y\cdot\sqrt{-\frac{c}{a}}~~~~;~~~~x^2=-y^2\cdot\frac{c}{a}$$
$$ -c\cdot y^2+b\cdot y\cdot\sqrt{-\frac{c}{a}}-c=0~~~~|:(-c)$$
$$ y^2 -\frac{1}{-c}\cdot b\cdot\sqrt{-\frac{c}{a}}\cdot y+1 =0$$
$$ y^2 + b\cdot\sqrt{-\frac{c}{a\cdot c^2}}\cdot y+1 =0$$
$$ y^2 + b\cdot\sqrt{-\frac{1}{ac}}\cdot y+1 =0$$
$$ y^2 + \frac{b}{\sqrt{-ac}}\cdot y+1 =0$$