http://www.jaicompris.com/lycee/math/...
Putting a quadratic function in vertex form - the 2 methods - first year advanced math course: f(x) = ax² + bx + c = a(x - α)² + β
Method using the formula for α: α = -b/2a
Method by completing the square (square completion)
Check with the vertex of the parabola that no mistakes have been made