1967 - Montreal, Canada - Expo '67, (Universal and International Exhibition of 1967) the most successful Fair ever, drawing more than 50 million visitors.
... 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 square; it is the ...