The twenty-second century comprises the years 2101-2200. This is different from the century known as the twenty-one hundreds, which comprises the years 2100-2199.
... so 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 ...