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.

\( 3(x + 4) = 3x + 12 \)

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.

\( a(b + c) = ab + ac \)
Key idea: Multiply the outside term by every term inside the bracket.

Step 1: Multiply each term inside the bracket

\( 4(x + 3) \)
\(4 \times x = 4x\)
\(4 \times 3 = 12\)
Answer: \(4x + 12\)
Exam tip: Never multiply just one term — always both.

Step 2: Be careful with subtraction

\( 5(x - 2) \)
\(5 \times x = 5x\)
\(5 \times (-2) = -10\)
Answer: \(5x - 10\)

Step 3: Watch out for negative brackets

\( -3(x + 4) \)
\(-3 \times x = -3x\)
\(-3 \times 4 = -12\)
Answer: \(-3x - 12\)
Exam tip: A negative outside changes all signs inside.

Expand then simplify

After expanding, you often need to combine like terms.

\( 3(x + 2) + 4x \)
Expand first: \(3x + 6 + 4x\)
Combine like terms: \(7x + 6\)
Answer: \(7x + 6\)
Combining like terms is covered in simplifying expressions.

Double brackets

When expanding two brackets, each term in the first bracket multiplies each term in the second bracket.

\( (x+2)(x+5) \)
Multiply: \(x \cdot x\), \(x \cdot 5\), \(2 \cdot x\), \(2 \cdot 5\)
This gives: \(x^2 + 5x + 2x + 10\)
Simplify: \(x^2 + 7x + 10\)
Exam tip: Make sure you include all four products.

Example Questions

Edexcel

Exam-style questions inspired by Edexcel GCSE Mathematics.

Edexcel

Expand \( 3(x + 4) \).

Edexcel

Expand \( 5(a - 2) \).

Edexcel

Expand \( -2(y + 6) \).

Edexcel

Expand \( 4(2x - 3) \).

Edexcel

Expand and simplify \( 6(3p + 2) \).

AQA

Exam-style questions based on the AQA GCSE Mathematics specification, focusing on accuracy and algebraic fluency.

AQA

Expand \( x(x + 5) \).

AQA

Expand \( (x + 3)(x + 4) \).

AQA

Expand \( (x + 7)(x - 2) \).

AQA

Expand and simplify \( (2x + 3)(x + 5) \).

AQA

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.

OCR

Expand \( (x + 5)^2 \).

OCR

Expand \( (x - 6)^2 \).

OCR

Expand \( (x + 3)(x - 3) \).

OCR

Expand and simplify \( (3x - 2)(2x + 5) \).

OCR

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

Incorrect

A student multiplies only the first term inside the bracket.

Correct

Every term inside the bracket must be multiplied. For example, \(3(x + 4) = 3x + 12\), not \(3x + 4\).

Forgetting to multiply a negative sign

Incorrect

A student does not apply the negative to all terms.

Correct

A negative sign in front of brackets changes the sign of every term. For example, \(-(x + 5) = -x - 5\).

Sign errors during multiplication

Incorrect

A student gets positive and negative results mixed up.

Correct

Check signs carefully: positive × positive = positive, negative × positive = negative, and negative × negative = positive.

Not simplifying after expanding

Incorrect

A student expands correctly but leaves like terms uncombined.

Correct

After expanding, always collect like terms to fully simplify the expression.

Missing a multiplication in double brackets

Incorrect

A student forgets to multiply one pair of terms in expressions like \((x + 2)(x + 3)\).

Correct

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.

Questions coming soon
Foundation

Foundation Practice

Start with single brackets and basic expansion.

Question 1

Expand: \(3(x + 4)\)

Games

Practise this topic with interactive games.

Games coming soon.

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.