Mathematics - Additional - 0606 CIE

Quadratic Inequalities

Overview

You can already solve a quadratic equation. A quadratic inequality asks a related but richer question: for which values of x is the expression positive, or negative? The answer is no longer a couple of points but a whole range of values, and finding that range turns out to be elegant once you see the structure.

In this lesson you will solve inequalities like \(x^2-x-6>0\) by first finding the roots, then deciding which regions satisfy the inequality using a quick sketch or a sign diagram. You will learn to express answers in the two standard shapes examiners expect: a single interval like \(-33\).

Objectives

  1. Find the solution set for quadratic inequalities, either graphically or algebraically.

Lesson Note

Many real questions ask not where something equals a target, but where it stays above or below it: when is a profit positive, when does a height exceed a limit, when is a quantity within a safe band. Quadratic inequalities answer exactly these questions, and the sketch-based method here also deepens your feel for the shape of a parabola.

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Lesson Evaluation

Congratulations on completing the lesson on Quadratic Inequalities. 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. What is the solution of x^2 - x - 6 > 0? A. -2 < x < 3 B. x < -2 or x > 3 C. -3 < x < 2 D. x < 2 or x > 3 Answer: B
  2. What is the solution of x^2 - x - 12 < 0? A. x < -3 or x > 4 B. -3 < x < 4 C. -4 < x < 3 D. x < 3 or x > 4 Answer: B
  3. The roots of a quadratic with a > 0 are -1 and 5. Where is the expression negative? A. x < -1 or x > 5 B. -1 < x < 5 C. x > 5 D. x < -1 Answer: B
  4. The roots of a quadratic with a > 0 are 2 and 6. Where is the expression positive? A. 2 < x < 6 B. x < 2 or x > 6 C. x < 6 D. x > 2 Answer: B
  5. Which of these is a valid way to write the solution of a quadratic inequality? A. -2 > x > 3 B. x < -2 or x > 3 C. 3 < x < -2 D. x = -2 or x = 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
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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

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