Remainder Theorem

A powerful tool to find the remainder without performing long division.

Introduction

When we divide a polynomial p(x) by another polynomial g(x), we get a quotient q(x) and a remainder r(x).
p(x) = g(x) × q(x) + r(x)
Degree of r(x) < Degree of g(x).

Statement of Remainder Theorem

If p(x) is any polynomial of degree greater than or equal to 1 and p(x) is divided by the linear polynomial (x - a), then the remainder is p(a).

Example

Find the remainder when p(x) = x⁴ + x³ - 2x² + x + 1 is divided by x - 1.
Here, divisor is x - 1, so a = 1.
Remainder = p(1) = (1)⁴ + (1)³ - 2(1)² + 1 + 1 = 1 + 1 - 2 + 1 + 1 = 2.

Practice Questions

Free Preview - 10 Questions

Test your understanding of the Remainder Theorem.

1 Find the remainder when x² - 2x + 4 is divided by x - 2.
  • A 2
  • B 4
  • C 0
  • D -2
Explanation:
Using Remainder Theorem, p(2) = (2)² - 2(2) + 4 = 4 - 4 + 4 = 4.
2 If p(x) is divided by x + 1, the remainder is:
  • A p(1)
  • B p(-1)
  • C p(0)
  • D -p(1)
Explanation:
Comparing x + 1 with x - a, we get a = -1. So remainder is p(-1).
3 What is the remainder when x³ + 3x² + 3x + 1 is divided by x + 1?
  • A 0
  • B 1
  • C 8
  • D -1
Explanation:
p(-1) = (-1)³ + 3(-1)² + 3(-1) + 1 = -1 + 3 - 3 + 1 = 0.
4 If p(x) = x³ - ax² + 6x - a is divided by x - a, remainder is:
  • A a
  • B 5a
  • C -5a
  • D 0
Explanation:
p(a) = a³ - a(a)² + 6a - a = a³ - a³ + 5a = 5a.
5 The remainder when 4x³ - 12x² + 14x - 3 is divided by 2x - 1 is:
  • A 0
  • B 1/2
  • C 3/2
  • D -3/2
Explanation:
Divisor 2x - 1 = 0 → x = 1/2.
p(1/2) = 4(1/8) - 12(1/4) + 14(1/2) - 3
= 1/2 - 3 + 7 - 3 = 1/2 + 1 = 3/2.
6 When p(x) is divided by x, the remainder is:
  • A p(0)
  • B p(1)
  • C p(x)
  • D 0
Explanation:
Checking x = 0 (since x - 0 = x), the remainder is p(0).
7 Check whether the polynomial p(x) = 4x³ + 4x² - x - 1 is a multiple of 2x + 1.
  • A Yes
  • B No
  • C Only for positive x
  • D None
Explanation:
Zero of 2x + 1 is -1/2.
p(-1/2) = 4(-1/8) + 4(1/4) - (-1/2) - 1
= -1/2 + 1 + 1/2 - 1 = 0.
Since remainder is 0, it is a multiple.
8 If x - 1 divides the polynomial kx² - 3x + k completely, find k.
  • A 3
  • B 3/2
  • C 2/3
  • D -3
Explanation:
Since it divides completely, remainder p(1) = 0.
k(1)² - 3(1) + k = 0
2k - 3 = 0 → k = 3/2.
9 If p(x) = x⁹⁹ + 1 is divided by x + 1, remainder is:
  • A 1
  • B 2
  • C 0
  • D -1
Explanation:
p(-1) = (-1)⁹⁹ + 1 = -1 + 1 = 0.
10 What is the remainder when x⁴ + 1 is divided by x - 1?
  • A 0
  • B 2
  • C 1
  • D -2
Explanation:
p(1) = (1)⁴ + 1 = 1 + 1 = 2.

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Remainder Theorem - Exam Preparation Strategy

When studying Remainder Theorem for your final board exams, it is critical to focus on the core concepts and fundamental formulas. Relying strictly on NCERT textbook solutions and practicing previous year questions (PYQs) is the proven methodology for scoring high marks. Avoid rote memorization and instead focus on the logical application of the theories presented in this chapter.

⚠️ Common Mistakes to Avoid

❓ Frequently Asked Questions

How can I quickly memorize the concepts of Remainder Theorem?

The most effective way is to create short, handwritten revision notes and continuously test your knowledge using our interactive Mock Tests. Spaced repetition and active recall are much better than passive reading.

What type of questions are most commonly asked from Remainder Theorem?

Board exams tend to favor conceptual application questions and direct formula-based derivations from the NCERT syllabus. Ensure you have solved every single exercise in the official textbook.

Is reading the NCERT book enough for this chapter?

Yes, the NCERT textbook is the absolute gold standard for board exams. However, to improve your speed and accuracy during the actual exam, you must supplement your reading by solving timed mock tests and objective questions.