Explain the use of the quadratic formula to solve quadratic equations.

To explain this to a student, I would start by explaining the general formula for a quadratic equation, (ax^2 + bx + c = 0). Then I would show using an example, how the a,b and c can be substituted with numbers. I would then check that they could arrange an equation into this layout if they were given one in the form of ax^2 + bx = -c for example.

Next I would state the quadratic formula, that will be given on formula sheets for gcse. I would then explain with an example, how a quadratic equation can be substituted into this, and then explain step by step how to solve it.

Next I would give the student an example question and ask them to try to solve it themselves as I gave guidance to check that they understood.

If relevant to the syllabus being studied, I would then explain why this is useful e.g. to find the x intercept of a graph. I would also give some scenarios where you can choose which of the two answers is the right one, such as when answers below zero are invalid.