Deliverance by James Dickey (in 2001, named as one of the 100 best English-language novels of the 20th century, as chosen by the editorial board of the Modern Library.)
... we add the square of b/(2a) to both sides, getting
<math>x^2+\frac{b}{a}x+\frac{b^2}{4a^2}=-\frac{c}{a}+\frac{b^2}{4a^2}.</math>
The left side is now a ...