KS3 Maths · Topic guide

Expanding Single Brackets

Expanding a single bracket means multiplying every term inside the bracket by the term directly outside it, using the distributive law a(b + c) = ab + ac. This applies whenever a number or letter sits immediately next to a bracket, and it is essential whenever the term outside is negative, since multiplying by a negative flips the sign of every term inside the bracket.

Year 7-9 (KS3)AlgebraNational Curriculum

Before you start

Make sure you're comfortable with these topics first:

Method

  1. Identify the term directly outside the bracket, including its sign.
  2. Multiply the outside term by the FIRST term inside the bracket.
  3. Multiply the outside term by the SECOND (and any further) term inside the bracket, keeping careful track of signs.
  4. Write the products in a row with the correct + or - sign between them.
  5. If the term outside the bracket is negative, remember that multiplying by a negative flips the sign of every term inside the bracket.
  6. Collect any like terms after expanding, if the expression contains more than one bracket or extra terms.

Worked example

Expand and simplify 5(2x + 3) - 3(x - 4).

  1. Expand the first bracket: 5(2x + 3) = 5 x 2x + 5 x 3 = 10x + 15.
  2. Expand the second bracket: -3(x - 4) = -3 x x + (-3) x (-4) = -3x + 12.
  3. Write the full expression: 10x + 15 - 3x + 12.
  4. Collect like terms: 10x - 3x = 7x, and 15 + 12 = 27.
  5. Final answer: 7x + 27.

Practice questions

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Q1Expand 3(x + 5).Show answer

Answer: 3x + 15

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Q2Expand 4(2x - 1).Show answer

Answer: 8x - 4

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Q3Expand -2(x + 6).Show answer

Answer: -2x - 12

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Q4Expand and simplify 2(x + 3) + 3(x + 1).Show answer

Answer: 5x + 9

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Q5Expand and simplify 6(x - 2) - 2(x - 5).Show answer

Answer: 4x - 2

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Q6Expand -3(2x - 4).Show answer

Answer: -6x + 12

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Q7Expand and simplify 4(3x + 2) - 5x.Show answer

Answer: 7x + 8

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Exam-style questions

Written in the style of a KS3 Maths exam paper, with a full mark scheme.

Q1[3 marks]

Expand and simplify 7(x + 2) - 3(x - 1).

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Q2[2 marks]

A student says that -4(x - 5) expands to -4x - 20. Show that the student is wrong, and give the correct expansion.

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Free printable worksheet

Want more practice on paper? Download the expanding single brackets worksheet pack - 5 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.

This topic is chapter 23 of KS3 Maths Workbook 1, the whole course as one free printable PDF.

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