For a quadratic equation of the form \(y = k{(x - a)^2} + b\), the following diagram shows the main properties: If k > 0, the vertex is a minimum turning point If k < 0, the vertex is a maximum ...

Everyone learns (and some readers maybe still remember) the quadratic ... form. If you read the actual paper, you’ll see how easy it is to symbolically derive the “old” standard formula.

If it doesn’t, the general rule is - if you can factorise it, then factorise it. If you can’t, use the quadratic formula.