Further Pure Mathematics - 4PM1 PearsonEdexcel

Functions Of The Roots Of A Quadratic Equation

Overview

What if you could discover properties of a quadratic's roots without ever solving the equation? The relationships between the coefficients and the roots of a quadratic give you exactly that power, letting you evaluate expressions involving the roots and even build entirely new equations from transformed roots.

In this topic you will master the sum and product of roots, learn to express higher-power symmetric functions in terms of these two building blocks, and practise the exam technique of forming a new quadratic whose roots are given as functions of the original ones. These skills appear on almost every 4PM1 paper and carry substantial marks.

Objectives

  1. Understand and use the relationships between roots and coefficients of ax^2 + bx + c = 0
  2. Form an equation with given roots expressed in terms of the original roots

Lesson Note

Given a quadratic equation, you can always find its roots by factorising or using the formula. But many exam questions ask you to work with the roots without finding them individually. Instead, you use two elegant relationships that connect the roots directly to the coefficients of the equation. These are sometimes called Vieta's formulas, and they unlock a whole family of powerful results.

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Lesson Evaluation

Congratulations on completing the lesson on Functions Of The Roots Of A Quadratic Equation. 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. The roots of 2x^2 - 10x + 7 = 0 are alpha and beta. What is the value of alpha + beta? A) -5 B) 5 C) 7/2 D) -7/2 Answer: B
  2. If the roots of x^2 + px + q = 0 are alpha and beta, which expression equals alpha^2 + beta^2? A) p^2 + 2q B) p^2 - 2q C) (p + q)^2 D) p^2 - q^2 Answer: B
  3. The roots of x^2 - 3x + 1 = 0 are alpha and beta. What is the value of 1/alpha + 1/beta? A) 1/3 B) 3 C) -3 D) 1 Answer: B
  4. The equation whose roots are 2alpha and 2beta, where alpha and beta are the roots of x^2 - 4x + 3 = 0, is: A) x^2 - 8x + 12 = 0 B) x^2 - 8x + 3 = 0 C) x^2 - 4x + 12 = 0 D) x^2 + 8x + 12 = 0 Answer: A
  5. The product of the roots of 5x^2 + 3x - 2 = 0 is: A) 3/5 B) -3/5 C) -2/5 D) 2/5 Answer: C

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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