Quadratic Functions(2) Solving quadratic equations through factorising. Checking to see if a quadratic equation will factorise.

Solving through factorisation Solving a quadratic equation through factorisation is usually the first choice method as it is the easiest. However, not all quadratic equations factorise and if they don’t, you need to use a different method.

Trick If you substitute the values of a, b and c into the expression b2 – 4ac and you get a square number then the equation definitely factorises, otherwise, it doesn’t.

Trick – an example a=5 b=14 c=-3 b2 – 4ac (14)2 – 4 x (5) x (-3) Discriminant (14)2 – 4 x (5) x (-3) 196 – (-60) = 256 This is a square number, so quadratic does factorise

Solving Quadratic Equations We will now look at solving quadratic equations using factorisation