Solving Quadratics by Factorising AS Maths

Concept… When we factorise a quadratic expression, we typically end up in the form (x + a)(x + b), where a and b are integers. If we are asked to solve a quadratic in the form (x + a)(x + b) = 0, we can set each factor equal to zero and solve separately. Why? Because we know that if we have two unknown values being multiplied and they = 0, then one or both of the values must equal zero. If (a)(b) = 0, then either a or b or both is zero.

Solving Quadratics Steps... Must be in standard form & set equal to zero! Factorise fully Set each factor equal to zero and solve separately

Example 1: Already in Factorised Form Solve. (a) (b) (c) Divide both sides by -2

Example 2: Factorise then solve (a) (b)

Example 2: Factor then solve (cont’d) (c) (d)

Factorising vs. Quadratic Formula Think you like this better than ?? Factorising can be quicker and seem easier than using the quadratic formula, but be careful – not all quadratics are easily factorised, so it is not a guaranteed method that will work every single time. On the flip side, the quadratic formula is longer and more tedious, but it works for ALL quadratics in every single case!

Independent Study: Complete the mymaths online assignment over: Solving Quadratics Copy & complete each question notebook, show all work, and mark in a colourful pen. DUE NEXT LESSON.