Pope Urban V makes the first attempt to move the Papacy back to Rome from Avignon. This move is reversed in 1370 when he is forced to return to Avignon and shortly afterwards dies.
... 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 perfect ...