The Factor And Remainder Theorems
Overview
How can you tell whether a linear expression divides exactly into a polynomial without carrying out the full long division? The factor theorem and the remainder theorem give you a direct shortcut: substitute a single value, and the answer tells you everything you need. These two results are the key tools for breaking cubic and higher-degree polynomials into simpler factors.
In this topic you will learn to test whether a given linear expression is a factor, find the remainder from any linear divisor, and combine these techniques with algebraic division to factorise cubics completely. These skills appear frequently on both papers of the Edexcel 4PM1 exam and connect directly to solving polynomial equations.
Objectives
- Know that if f(x) = 0 when x = a, then (x - a) is a factor of f(x)
- Factorise cubic expressions when a factor has been provided
- Determine the remainder when the polynomial f(x) is divided by (ax + b) or (ax - b)
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on The Factor And Remainder Theorems. 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.
- If f(x) = x^3 - 3x^2 + 2x - 6 and f(3) = 0, which of the following is a factor of f(x)? A) (x + 3) B) (x - 3) C) (x - 6) D) (x + 1) Answer: B
- When f(x) = x^3 + x^2 - 2x + 1 is divided by (x - 1), the remainder is: A) 0 B) 1 C) -1 D) 3 Answer: B
- Which value of x should you substitute to test whether (x + 4) is a factor of f(x)? A) x = 4 B) x = -4 C) x = 1/4 D) x = -1/4 Answer: B
- The polynomial f(x) = 2x^3 - x^2 + kx + 6 has (x - 2) as a factor. What is k? A) -5 B) -7 C) 5 D) 7 Answer: A
- If the remainder when f(x) is divided by (x - a) is equal to zero, then: A) a is a coefficient of f(x) B) (x - a) is a factor of f(x) C) f(x) has degree a D) f(x) has no real roots 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.
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.
Practice Mock Questions
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