Expanding single brackets

Distribute positive and negative factors across sums and differences.

Key formulas

k(a+b)=ka+kbk(a+b)=ka+kb

What this lesson covers

This lesson builds Secondary 2–3 skill in single bracket expand. Read the key formulas, study the worked example, then attempt the written practice and the four-question MCQ review.

Method

Write every step. Name the rule you use (single bracket expand) before substituting numbers. Keep units and signs visible until the final sentence.

Common mistakes

Students often rush the sign, use the wrong percentage base, or cancel terms instead of factors. Pause after each line and ask whether the step is reversible.

Exam habit

Underline the question verb (simplify, solve, factorise, find). Box the final answer and, where sensible, substitute back for a quick check.

Worked example

Worked example — single bracket expand

Problem. Apply the method for single bracket expand with the numbers 8 and 5.

Solution. Identify the rule for single bracket expand. Substitute 8 and 5 carefully with signs in brackets if needed. Complete each operation on a new line. State the final answer clearly and check by reversing one step.

Review quiz

1 / 4

Warm-up on single bracket expand: what is 4+4?

Practice questions

  1. Practice 1 on single bracket expand: compute with the value 32.
  2. Practice 2 on single bracket expand: change the numbers and repeat the same method.
  3. Practice 3 on single bracket expand: write one sentence explaining the key rule.
  4. Practice 4 on single bracket expand: invent a similar exam-style question and solve it.

Study notes

What is the main idea of single bracket expand?

Apply the stated formula or rule with clear steps, then check by reversing or substituting.

How should I revise this topic?

Cover the worked example, redo the practice without notes, then complete the MCQ set and log any wrong options.

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