Role-playing games often use a common set of creatures that are easily recognizeable and have pre-determined traits. Most are based on mythology in some form or other. The Dungeons & Dragons Monster Manual contains many of these as well.
... is equivalent to
<math>x^2+\frac{b}{a}x=-\frac{c}{a}.</math>
The equation is now in a form in which we can conveniently complete the square[?]. T ...