There are two ways to solve an equation with brackets. You can expand first: 4(x + 3) = 32 becomes 4x + 12 = 32, then 4x = 20 and x = 5.
Or you can divide first: 4(x + 3) = 32, so x + 3 = 8 and x = 5. Dividing first is quicker when the number outside divides the other side exactly. When there are brackets on both sides, expand them all, then collect the x terms on one side.
Worked example
Solve 3(x − 2) = 21
- Divide both sides by 3: x − 2 = 7.
- Add 2 to both sides.
Answer:x = 9
Key words
- bracket
- groups an expression
- expand
- multiply out
- both sides
- the expressions left and right of the equals sign
Practise this
New questions every time.
Common Core-referenced: 7.EE.B.4a