Factorising is a way of 'converting' an equation into a form with brackets in order to make it more useful and easier to manipulate. It is the reverse of expanding an equation.

For example:

To factorise the quadratic x^{2}+5x+6, you need to look for a pair of numbers that multiply to give 6 and at the same time, add up to 5.

In this case, this is 3 and 2.

This means we can factorise and write the equation x^{2}+5x+6 as (x+2)(x+3).