Intermediate · 12 min
Expanding and factorising
Distribute multiplication over a sum and reverse the process.
Multiply every term
A number outside brackets multiplies each term inside them. Keep the sign of every term when expanding.
Worked example
3(x − 2) = 3x − 6
Take out a common factor
Factorising reverses expansion. Find a factor shared by every term, then divide each term by it inside the brackets.
Worked example
6x + 9 = 3(2x + 3)
Check both directions
- Expand 5(2x − 3).
- Factorise your result, then substitute x = 4 in both forms to check they agree.