Type a polynomial in , such as x^3 - 6x^2 + 11x - 6. Try to find one factor yourself before you open the working.
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How to factorise a cubic by hand
- Find a root. Try the factors of the constant term: for . Here .
- Use the factor theorem. , so is a factor.
- Divide. .
- Factorise the quadratic. .
Practise with real exam questions
- O Level 4037 factor and remainder theorem: unknown coefficients, then factorise and solve.
Questions students ask
It finds a root a, so (x - a) is a factor by the factor theorem, divides the cubic by it, then factorises the quadratic that is left.
No. Many have roots that are surds or not real at all. The factoriser shows the roots so you can see which case you have.