Quadratic equations can be solved by the following methods:
Look at the National 4 factorising section before continuing.
When a question asks you to 'solve' a quadratic equation, this means that you are to find the roots of the quadratic. In other words, where does the parabola cut the x-axis?
As a graph cuts the axis when the y coordinate is zero, then we substitute into the quadratic equation and use algebra to solve.
We need to factorise the trinomial.
When factorised this is .
and are multiplying to give zero, therefore one of these brackets must be equal to zero.
Therefore are the roots of quadtratic equations.
Now try the example question below.
Factorise the trinomial and then find the two possible values.