You should know the following:

• A quadratic is normally given in one of three forms:  (expanded / normal form)  (factorised form)  (completed square form)
• The quadratic formula, , can be used to find the solution(s) to any quadratic equation (if it has any), and must be learned off by heart.
• The discriminant, , indicated the number of roots: means two roots; means one root; means no real roots.

Use the Step-by-Step tool below to walk through the steps for completing the square of any quadratic expression.