Factorising quadratic expressions is the opposite of multiplying out the brackets. For example the expression (x+1)(x+3) can be multiplied out to give x^2+4x+3. Going the other way or reversing this process is called factorising.

## Summary/Background

The ability to factorise quadratic functions is essential to making sound progress in advanced
mathematics. It is a skill. You get better with practise.

## Software/Applets used on this page

## Glossary

### quadratic

A mathematical expression of the 2nd degree; having a x² term but no higher one.

### union

The union of two sets A and B is the set containing all the elements of A and B.