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Chapter 8 · Class 9 Mathematics

Polynomials — Important Questions

25 questions With answers CBSE format

SUMMARY: The chapter on Polynomials introduces students to the concept of polynomials, their types, and operations on them.
KEY TOPICS: definition of polynomials, degree of a polynomial, zeroes of a polynomial, factorization of polynomials, algebraic identities, remainder theorem, factor theorem, types of polynomials (linear, quadratic, cubic), addition and subtraction of polynomials, multiplication of polynomials.

Q1 1 Mark

Which of the following is a polynomial?

A3x + 2
B2/x + 5
C√x + 4
Dln(x) + 1
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Correct answer: Option 1 — 3x + 2
Q2 1 Mark

What is the degree of the polynomial 4x^3 - 2x^2 + x - 7?

A2
B3
C1
D4
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Correct answer: Option 2 — 3
Q3 1 Mark

If p(x) = x^2 - 5x + 6, what are the zeroes of the polynomial?

A2 and 3
B-2 and -3
C1 and 6
D0 and 6
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Correct answer: Option 1 — 2 and 3
Q4 1 Mark

Which of the following is an algebraic identity?

A(a + b)^2 = a^2 + b^2
B(a + b)^2 = a^2 + 2ab + b^2
C(a - b)^2 = a^2 - b^2
D(a + b)(a - b) = a^2 + b^2
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Correct answer: Option 2 — (a + b)^2 = a^2 + 2ab + b^2
Q5 1 Mark

According to the Remainder Theorem, what is the remainder when the polynomial f(x) = 2x^3 - 3x^2 + x - 5 is divided by (x - 2)?

A-5
B-3
C1
D3
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Correct answer: Option 3 — 1
Q6 3 Marks

Define a polynomial and give an example.

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A polynomial is an algebraic expression that consists of variables raised to non-negative integer powers and coefficients. For example, 3x^2 + 2x + 1 is a polynomial.
Q7 3 Marks

What is the degree of the polynomial 4x^3 - 5x + 7?

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The degree of a polynomial is the highest power of the variable in the expression. For the polynomial 4x^3 - 5x + 7, the degree is 3.
Q8 3 Marks

Explain the Remainder Theorem and provide an example.

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The Remainder Theorem states that when a polynomial f(x) is divided by (x - a), the remainder is f(a). For example, if f(x) = x^2 + 2x + 1 and we divide by (x - 1), the remainder is f(1) = 1^2 + 2(1) + 1 = 4.
Q9 3 Marks

What are the zeroes of the polynomial f(x) = x^2 - 5x + 6?

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The zeroes of the polynomial f(x) = x^2 - 5x + 6 can be found by factoring it as (x - 2)(x - 3). Thus, the zeroes are x = 2 and x = 3.
Q10 3 Marks

Use the Factor Theorem to determine if x - 2 is a factor of the polynomial f(x) = x^3 - 3x^2 + 4. Show your working.

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To use the Factor Theorem, we evaluate f(2). f(2) = 2^3 - 3(2^2) + 4 = 8 - 12 + 4 = 0. Since f(2) = 0, x - 2 is a factor of the polynomial.
Q11 6 Marks

Define a polynomial and explain its degree. Provide examples of different types of polynomials based on their degrees.

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A polynomial is an algebraic expression that consists of variables raised to non-negative integer powers and coefficients. The degree of a polynomial is the highest power of the variable in the expression. For example, the polynomial 3x^4 + 2x^3 - x + 7 is a polynomial of degree 4, as the highest power of x is 4. Other examples include linear polynomials like 2x + 3 (degree 1) and quadratic polynomials like x^2 - 5x + 6 (degree 2).
Q12 6 Marks

What are the zeroes of a polynomial? Describe how to find the zeroes of a quadratic polynomial using the factorization method.

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The zeroes of a polynomial are the values of the variable that make the polynomial equal to zero. For a quadratic polynomial of the form ax^2 + bx + c, the zeroes can be found by factorizing the polynomial into the form (px + q)(rx + s) = 0. For instance, to find the zeroes of the polynomial x^2 - 5x + 6, we can factor it as (x - 2)(x - 3) = 0, giving us the zeroes x = 2 and x = 3.
Q13 6 Marks

Explain the Remainder Theorem and provide an example to illustrate how it is applied to find the remainder of a polynomial when divided by a linear polynomial.

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The Remainder Theorem states that if a polynomial f(x) is divided by a linear polynomial of the form (x - a), the remainder of this division is f(a). For example, consider the polynomial f(x) = 2x^3 - 3x^2 + 4 and we want to find the remainder when it is divided by (x - 1). According to the theorem, we evaluate f(1) = 2(1)^3 - 3(1)^2 + 4 = 2 - 3 + 4 = 3. Thus, the remainder is 3.
Q14 6 Marks

Discuss the Factor Theorem and how it relates to the zeroes of a polynomial. Provide an example to demonstrate its application.

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The Factor Theorem states that a polynomial f(x) has a factor (x - a) if and only if f(a) = 0. This means that if a is a zero of the polynomial, then (x - a) is a factor of f(x). For example, consider the polynomial f(x) = x^2 - 4. To check if (x - 2) is a factor, we evaluate f(2) = 2^2 - 4 = 0. Since f(2) = 0, by the Factor Theorem, (x - 2) is indeed a factor of f(x), and we can factor the polynomial as (x - 2)(x + 2).
Q15 6 Marks

Perform the addition and multiplication of the polynomials (3x^2 + 2x - 1) and (x^2 - 4x + 5). Show all steps in your calculations.

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To add the polynomials (3x^2 + 2x - 1) and (x^2 - 4x + 5), we combine like terms: (3x^2 + x^2) + (2x - 4x) + (-1 + 5) = 4x^2 - 2x + 4. For multiplication, we use the distributive property: (3x^2 + 2x - 1)(x^2 - 4x + 5) = 3x^2(x^2) + 3x^2(-4x) + 3x^2(5) + 2x(x^2) + 2x(-4x) + 2x(5) - 1(x^2) + 1(4x) - 1(5). This results in 3x^4 - 12x^3 + 15x^2 + 2x^3 - 8x^2 + 10x - x^2 + 4x - 5, which simplifies to 3x^4 - 10x^3 + 6x^2 + 14x - 5.
Q16 1 Mark

Assertion (A): A polynomial of degree 3 can have at most 3 zeroes.

Reason (R): The degree of a polynomial determines the maximum number of zeroes it can have.

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Correct answer: Option 1 — Both A and R are true, and R is the correct explanation of A.
Q17 1 Mark

Assertion (A): The expression 2x^2 + 3x - 5 is a quadratic polynomial.

Reason (R): A quadratic polynomial is defined as a polynomial of degree 2.

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Correct answer: Option 1 — Both A and R are true, and R is the correct explanation of A.
Q18 1 Mark

Assertion (A): The factor theorem states that if 'p(x)' is a polynomial and 'a' is a zero of 'p(x)', then (x - a) is a factor of 'p(x)'.

Reason (R): The factor theorem is a specific case of the remainder theorem.

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Correct answer: Option 2 — Both A and R are true, but R is not the correct explanation of A.
Q19 1 Mark

Assertion (A): The polynomial 4x^3 - 2x + 1 is a linear polynomial.

Reason (R): A linear polynomial is defined as a polynomial of degree 1.

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Correct answer: Option 3 — A is true, but R is false.
Q20 1 Mark

Assertion (A): The sum of two polynomials is always a polynomial.

Reason (R): The set of polynomials is closed under addition.

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Correct answer: Option 1 — Both A and R are true, and R is the correct explanation of A.
Q21 1 Mark

Statement 1: A polynomial of degree 2 is called a quadratic polynomial.

Statement 2: The zeroes of a polynomial are the values of the variable that make the polynomial equal to 1.

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Correct answer: Option 2 — Only Statement 1 is true.
Q22 1 Mark

Statement 1: The factor theorem states that if a polynomial f(x) has a factor (x - a), then f(a) = 0.

Statement 2: The degree of a polynomial is determined by the highest power of its variable.

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Correct answer: Option 1 — Both statements are true.
Q23 1 Mark

Statement 1: The polynomial 3x^3 + 2x^2 - x + 5 is a cubic polynomial.

Statement 2: The sum of two polynomials is always a polynomial of the same degree as the polynomial with the higher degree.

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Correct answer: Option 1 — Both statements are true.
Q24 1 Mark

Statement 1: The expression x^2 - 4 can be factored as (x - 2)(x + 2).

Statement 2: A linear polynomial can have more than one zero.

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Correct answer: Option 3 — Only Statement 2 is true.
Q25 1 Mark

Statement 1: The remainder theorem can be used to find the remainder of a polynomial when divided by (x - a).

Statement 2: All polynomials are continuous functions.

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Correct answer: Option 1 — Both statements are true.

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