Mathematics (9-1) - 0980 CIE

Surds

Overview

A surd is a root that cannot be simplified to a whole number, such as \(\sqrt{2}\) or \(\sqrt{5}\). Surds let you keep answers exact rather than rounding, which matters whenever a question asks for an exact value, and they are the natural language of Pythagoras and trigonometry results.

In this lesson (Extended tier) you will simplify surds, multiply and add them where possible, and rationalise a denominator so that no surd is left underneath a fraction. These techniques keep working tidy and answers exact.

Objectives

  1. Understand and use surds, including simplifying expressions.
  2. Rationalise the denominator.

Lesson Note

Writing \(\sqrt{50}\) as \(5\sqrt{2}\) is both neater and exact, and leaving an answer as a surd avoids the rounding error a decimal would introduce. Surds appear throughout geometry and trigonometry, so handling them confidently keeps later work exact.

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Lesson Evaluation

Congratulations on completing the lesson on Surds. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. Simplify √50. A. 5√2 B. 2√5 C. 25√2 D. 10√5 Answer: A
  2. Work out √3 x √12. A. √15 B. 6 C. 36 D. 4√3 Answer: B
  3. Simplify 2√5 + 3√5. A. 5√10 B. 6√5 C. 5√5 D. 5 Answer: C
  4. Rationalise the denominator of 1/√2. A. √2 B. 2/√2 C. √2/2 D. 1/2 Answer: C
  5. Which expression cannot be simplified? A. √8 B. √2 + √3 C. √2 x √8 D. 4√3 - √3 Answer: B

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

Want to practice mock questions on Surds? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.

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