Expand: \(3(x + 4)\)
Expanding Brackets
Expanding brackets means multiplying expressions correctly to remove brackets. It is closely linked to simplifying expressions and factorising, and is an essential step in algebraic manipulation.
Overview
Expanding brackets means multiplying the term outside the bracket by every term inside the bracket.
This is a key GCSE algebra skill because it appears in simplifying expressions, factorising, solving equations and working with quadratics.
What you should understand after this topic
- Understand what expanding brackets means
- Expand a single bracket correctly
- Work accurately with negative numbers
- Expand and then simplify expressions
- Understand how double brackets work at a basic level
Key Definitions
Bracket
A group of terms written together, such as \(x + 5\).
Expand
Multiply out the bracket so the expression no longer stays in bracket form.
Term
One part of an expression, separated by + or − signs.
Coefficient
The number multiplying the variable, such as 4 in \(4x\).
Expression
A mathematical phrase with numbers, letters and operations.
Simplify
Collect like terms and write the final answer in its shortest correct form.
Key Rules
Multiply every term
\(2(x+5)=2x+10\)
Keep signs carefully
\(3(x-4)=3x-12\)
Negative outside changes signs
\(-2(x+3)=-2x-6\)
Simplify afterwards if needed
\(2(x+4)+x=3x+8\)
Quick Pattern Check
One term outside, two inside
\(5(a+2)\)
One term outside, subtraction inside
\(4(y-7)\)
Negative outside
\(-3(2x+1)\)
Expand then simplify
\(2(x+3)+4x\)
How to Solve
What does expanding brackets mean?
Expanding brackets means multiplying everything inside the bracket by the term outside. This is based on the distributive property.
Step 1: Multiply each term inside the bracket
Step 2: Be careful with subtraction
Step 3: Watch out for negative brackets
Expand then simplify
After expanding, you often need to combine like terms.
Double brackets
When expanding two brackets, each term in the first bracket multiplies each term in the second bracket.
Example Questions
Edexcel
Exam-style questions inspired by Edexcel GCSE Mathematics.
Expand \( 3(x + 4) \).
Expand \( 5(a - 2) \).
Expand \( -2(y + 6) \).
Expand \( 4(2x - 3) \).
Expand and simplify \( 6(3p + 2) \).
AQA
Exam-style questions based on the AQA GCSE Mathematics specification, focusing on accuracy and algebraic fluency.
Expand \( x(x + 5) \).
Expand \( (x + 3)(x + 4) \).
Expand \( (x + 7)(x - 2) \).
Expand and simplify \( (2x + 3)(x + 5) \).
A student expands \( (x + 4)^2 \) as \( x^2 + 16 \). Explain the mistake and give the correct answer.
OCR
Exam-style questions aligned with OCR GCSE Mathematics, emphasising reasoning, negative signs, and special products.
Expand \( (x + 5)^2 \).
Expand \( (x - 6)^2 \).
Expand \( (x + 3)(x - 3) \).
Expand and simplify \( (3x - 2)(2x + 5) \).
Expand \( -3(x - 4) \).
Exam Checklist
Step 1
Check how many terms are inside the bracket.
Step 2
Multiply the outside term by every inside term.
Step 3
Keep positive and negative signs correct.
Step 4
Simplify the final expression if needed.
Most common exam mistakes
Missing a term
Only multiplying one term inside the bracket instead of all of them.
Negative signs
Forgetting that a negative outside affects every term inside.
Final simplification
Leaving the answer unsimplified when like terms can still be collected.
Double brackets
Skipping one of the four products.
Common Mistakes
These are common mistakes students make when expanding brackets in GCSE Maths.
Not multiplying every term
A student multiplies only the first term inside the bracket.
Every term inside the bracket must be multiplied. For example, \(3(x + 4) = 3x + 12\), not \(3x + 4\).
Forgetting to multiply a negative sign
A student does not apply the negative to all terms.
A negative sign in front of brackets changes the sign of every term. For example, \(-(x + 5) = -x - 5\).
Sign errors during multiplication
A student gets positive and negative results mixed up.
Check signs carefully: positive × positive = positive, negative × positive = negative, and negative × negative = positive.
Not simplifying after expanding
A student expands correctly but leaves like terms uncombined.
After expanding, always collect like terms to fully simplify the expression.
Missing a multiplication in double brackets
A student forgets to multiply one pair of terms in expressions like \((x + 2)(x + 3)\).
In double brackets, every term in the first bracket must multiply every term in the second bracket. Use a systematic method such as FOIL or a grid.
Try It Yourself
Practise expanding single and double algebraic brackets.
Foundation Practice
Start with single brackets and basic expansion.
Expand: \(5(x + 2)\)
Expand: \(4(x - 3)\)
Expand: \(7(y + 5)\)
Expand: \(2(3x + 4)\)
Expand: \(3(2a - 1)\)
A student says \(3(x + 4) = 3x + 4\). What mistake did they make?
Expand: \(6(2x + 3)\)
Which is equal to \(5(x + 6)\)?
Expand: \(9(x - 2)\)
Higher Practice
Expand double brackets and handle algebraic multiplication.
Expand: \((x + 3)(x + 2)\)
Expand: \((x + 4)(x + 1)\)
Expand: \((x + 5)(x - 2)\)
Expand: \((x - 3)(x + 6)\)
Expand: \((2x + 3)(x + 4)\)
Expand: \((3x + 2)(x + 5)\)
A student expands \((x + 2)(x + 3)\) to \(x^2 + 6\). What did they miss?
Expand: \((x - 4)(x - 3)\)
Which expression expands to \(x^2 + 9x + 20\)?
Expand: \((2x - 3)(x + 7)\)
Expand: \((x + 3)^2\)
Expand: \((x + 5)^2\)
Expand: \((x - 4)^2\)
A student says \((x + 3)^2 = x^2 + 9\). What mistake did they make?
Expand: \((x + 2)(x - 2)\)
Expand: \((2x + 3)^2\)
Games
Practise this topic with interactive games.
Frequently Asked Questions
What does expanding mean?
Multiplying out brackets.
How do I expand double brackets?
Multiply each term in the first bracket by each term in the second.
What common mistake occurs?
Forgetting to multiply all terms.