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Polynomials

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CBSE Learning Objectives – Key Concepts & Skills You Must Know

Learning Objectives

  • Understand the definition and terminology related to polynomials.
  • Identify and classify polynomials based on their degree (linear, quadratic, cubic).
  • Apply the Remainder Theorem and Factor Theorem in polynomial factorization.
  • Utilize algebraic identities for simplifying and factorizing expressions.
  • Expand expressions using the identity for the square of a sum.
  • Factor polynomials using known identities and theorems.

CBSE Revision Notes & Quick Summary for Last-Minute Study

Chapter 2: Polynomials

2.1 Introduction

  • Study of algebraic expressions, operations, and factorization.
  • Introduction to polynomials and related terminology.
  • Overview of the Remainder Theorem and Factor Theorem.
  • Exploration of algebraic identities and their applications.

2.2 Polynomials in One Variable

  • Definition of a Variable: A symbol that can take any real value (e.g., x, y, z).
  • Algebraic Expressions: Examples include 2x, 3x, -x, etc.
  • Constants vs. Variables: Constants remain unchanged, while variables can change.

Types of Polynomials

  1. Linear Polynomials (Degree 1):
    • Form: ax + b (where a ≠ 0)
    • Examples: 4x + 5, 2y, 3u
  2. Quadratic Polynomials (Degree 2):
    • Form: ax² + bx + c (where a ≠ 0)
    • Examples: 5 - y², 4y + 5y²
  3. Cubic Polynomials (Degree 3):
    • Form: ax³ + bx² + cx + d (where a ≠ 0)
    • Examples: 4x³, 2x³ + 1
  4. General Polynomial (Degree n):
    • Form: aₙxⁿ + aₙ₋₁xⁿ⁻¹ + ... + a₁x + a₀ (where aₙ ≠ 0)
    • The zero polynomial has an undefined degree.

Polynomials in Multiple Variables

  • Examples: x² + y² + xyz (three variables), p² + q¹⁰ + r (three variables).

2.5 Algebraic Identities

  • Identity I: (x + y)² = x² + 2xy + y²
  • Identity II: Not specified in the excerpts.
  • Identity III: Not specified in the excerpts.
  • Identity IV: (x + a)(x + b) = x² + (a + b)x + ab
  • Identity V: (x + y + z)² = x² + y² + z² + 2xy + 2yz + 2zx

Examples of Using Identities

  1. Example 11:
    • Find products using identities:
      • (x + 3)(x + 3) = x² + 6x + 9
      • (x - 3)(x + 5) = x² + 2x - 15
  2. Example 14:
    • Expand (3a + 4b + 5c)² using Identity V.
    • Result: 9a² + 16b² + 25c² + 24ab + 40bc + 30ac
  3. Example 16:
    • Factorize 4x² + y² + z² - 4xy - 2yz + 4xz using Identity V.
    • Result: (2x - y + z)²

Important Notes

  • The degree of a polynomial indicates its highest exponent.
  • The structure of polynomials varies based on their degree and number of terms.

CBSE Quiz & Practice Test – MCQs, True/False Questions with Solutions

Multiple Choice Questions

A.

4-4

B.

55

C.

33

D.

2-2
Correct Answer: A

Solution:

The coefficient of x2x^2 in the polynomial p(x)=x34x2+5x2p(x) = x^3 - 4x^2 + 5x - 2 is 4-4.

A.

x3-x^3

B.

4x24x^2

C.

7x7x

D.

5x5x
Correct Answer: D

Solution:

The polynomial x3+4x2+7x2-x^3 + 4x^2 + 7x - 2 does not contain the term 5x5x. The terms are x3-x^3, 4x24x^2, 7x7x, and 2-2.

A.

3

B.

5

C.

7

D.

0
Correct Answer: A

Solution:

The coefficient of x2x^2 in the polynomial 3x2+5x+73x^2 + 5x + 7 is 3.

A.

00

B.

2x+32x + 3

C.

55

D.

x2x+1x^2 - x + 1
Correct Answer: C

Solution:

A constant polynomial is a polynomial of degree 0, which means it does not have any variable terms. The expression 55 is a constant polynomial. The zero polynomial 00 is also considered a constant polynomial, but it is a special case.

A.

-5

B.

6

C.

-4

D.

8
Correct Answer: A

Solution:

The term with t3t^3 in the polynomial r(t)r(t) is 5t3-5t^3. Therefore, the coefficient of t3t^3 is -5.

A.

x32x+1x^3 - 2x + 1

B.

3y2+5y3y^2 + 5y

C.

x+3\sqrt{x} + 3

D.

t2+4t^2 + 4
Correct Answer: C

Solution:

The expression x+3\sqrt{x} + 3 can be written as x1/2+3x^{1/2} + 3, where the exponent 1/21/2 is not a whole number. Therefore, it is not a polynomial. Hence, option_c is correct.

A.

4-4

B.

55

C.

33

D.

2-2
Correct Answer: A

Solution:

In the polynomial r(t)=t34t2+5t2r(t) = t^3 - 4t^2 + 5t - 2, the coefficient of t2t^2 is 4-4. Hence, option_a is correct.

A.

-1

B.

4

C.

7

D.

-2
Correct Answer: B

Solution:

The coefficient of x2x^2 in the polynomial x3+4x2+7x2-x^3 + 4x^2 + 7x - 2 is 4.

A.

20 square units

B.

25 square units

C.

30 square units

D.

35 square units
Correct Answer: B

Solution:

The area of a square is given by side \times side. Therefore, the area is 5 \times 5 = 25 square units.

A.

2x22x^2 square units

B.

4x24x^2 square units

C.

x2+4xx^2 + 4x square units

D.

x2x^2 square units
Correct Answer: B

Solution:

The original area is x2x^2 square units. Doubling the side length gives a new side length of 2x2x, so the new area is (2x)2=4x2(2x)^2 = 4x^2 square units.

A.

55 units

B.

1010 units

C.

1515 units

D.

2020 units
Correct Answer: D

Solution:

The perimeter of a square with side length xx is 4x4x. When the side length is increased to x+5x + 5, the new perimeter is 4(x+5)=4x+204(x + 5) = 4x + 20. The increase in perimeter is 2020 units.

A.

x - 1

B.

x + 2

C.

x - 3

D.

x + 4
Correct Answer: A

Solution:

By trial, p(1)=0p(1) = 0, so x1x - 1 is a factor of p(x)p(x).

A.

x1x - 1

B.

x+1x + 1

C.

x2x - 2

D.

x+2x + 2
Correct Answer: A

Solution:

By substituting x=1x = 1 into f(x)f(x), we find f(1)=144(1)3+6(1)24(1)+1=0f(1) = 1^4 - 4(1)^3 + 6(1)^2 - 4(1) + 1 = 0. Thus, x1x - 1 is a factor of f(x)f(x).

A.

7-7

B.

1414

C.

8-8

D.

11
Correct Answer: A

Solution:

The coefficient of t2t^2 in the polynomial p(t)=t37t2+14t8p(t) = t^3 - 7t^2 + 14t - 8 is 7-7.

A.

x2x^2 square units

B.

2x2x square units

C.

4x4x square units

D.

x3x^3 square units
Correct Answer: A

Solution:

The area of a square is given by the formula side \times side, which is x×x=x2x \times x = x^2 square units.

A.

0

B.

1

C.

-1

D.

2
Correct Answer: C

Solution:

By the Remainder Theorem, the remainder of r(t)r(t) divided by t1t - 1 is r(1)r(1). Calculating r(1)=132(1)2+12=1r(1) = 1^3 - 2(1)^2 + 1 - 2 = -1. Therefore, the remainder is -1.

A.

x3+x2+x+1x^3 + x^2 + x + 1

B.

x4+3x3+3x2+x+1x^4 + 3x^3 + 3x^2 + x + 1

C.

x2+2x+1x^2 + 2x + 1

D.

x31x^3 - 1
Correct Answer: A

Solution:

Using the Factor Theorem, (x+1)(x+1) is a factor if the polynomial evaluates to zero at x=1x = -1. For x3+x2+x+1x^3 + x^2 + x + 1, substituting x=1x = -1 gives (1)3+(1)2+(1)+1=0(-1)^3 + (-1)^2 + (-1) + 1 = 0.

A.

10 units

B.

15 units

C.

20 units

D.

25 units
Correct Answer: C

Solution:

The perimeter of a square is given by 4 times the length of one side. So, 4 \times 5 = 20 units.

A.

Splitting the middle term

B.

Using the quadratic formula

C.

Completing the square

D.

All of the above
Correct Answer: D

Solution:

The polynomial q(y)=y25y+6q(y) = y^2 - 5y + 6 can be factorized by splitting the middle term, using the quadratic formula, or completing the square. All methods are applicable for quadratic polynomials.

A.

7

B.

x + 1

C.

x^2 - x + 7

D.

3x
Correct Answer: A

Solution:

A constant polynomial is a polynomial that does not contain any variables. The expression '7' is a constant polynomial.

A.

-4

B.

5

C.

1

D.

-6
Correct Answer: A

Solution:

In the polynomial x34x2+5x6x^3 - 4x^2 + 5x - 6, the coefficient of x2x^2 is -4.

A.

-4

B.

4

C.

5

D.

-5
Correct Answer: A

Solution:

The coefficient of x^2 in the polynomial x^3 - 4x^2 + 5x - 6 is -4.

A.

6 units

B.

7 units

C.

8 units

D.

9 units
Correct Answer: B

Solution:

The perimeter of a square is 4 times the length of one side. Therefore, side length = 28/4 = 7 units.

A.

0

B.

1

C.

2

D.

-1
Correct Answer: A

Solution:

By the Remainder Theorem, the remainder of the division of q(y)q(y) by y1y - 1 is q(1)=133(1)2+3(1)1=0q(1) = 1^3 - 3(1)^2 + 3(1) - 1 = 0. Therefore, the remainder is 0.

A.

x - 1

B.

x - 2

C.

x - 3

D.

x - 4
Correct Answer: A

Solution:

To determine the factor, we use the Factor Theorem. We find p(1)=136(1)2+11(1)6=0p(1) = 1^3 - 6(1)^2 + 11(1) - 6 = 0. Therefore, x1x - 1 is a factor of p(x)p(x).

A.

x2x^2 square units

B.

4x4x square units

C.

2x2x square units

D.

xx square units
Correct Answer: A

Solution:

The area of a square is given by the square of its side length. Therefore, if the side length is xx units, the area is x2x^2 square units.

A.

x1x - 1

B.

x2x - 2

C.

x3x - 3

D.

x4x - 4
Correct Answer: C

Solution:

To find the factors of p(x)p(x), we can use the Factor Theorem. If p(c)=0p(c) = 0, then xcx - c is a factor of p(x)p(x). Evaluating p(x)p(x) at x=3x = 3, we have p(3)=335(3)2+6(3)=2745+18=0p(3) = 3^3 - 5(3)^2 + 6(3) = 27 - 45 + 18 = 0. Thus, x3x - 3 is a factor.

A.

(x+3)2(x+3)^2

B.

x2+6x+9x^2 + 6x + 9

C.

4x+124x + 12

D.

x2+9x^2 + 9
Correct Answer: A

Solution:

The new side length of the square is x+3x + 3. Therefore, the new area is (x+3)2=x2+6x+9(x+3)^2 = x^2 + 6x + 9. Hence, option_a is correct.

A.

x - 1

B.

x + 2

C.

x - 3

D.

x + 1
Correct Answer: A

Solution:

By the Factor Theorem, if p(1)=0p(1) = 0, then x1x - 1 is a factor. Calculating p(1)p(1) gives 0.

A.

3x^2 + 5x + 7

B.

x + \frac{1}{x}

C.

\sqrt{x} + 3

D.

\frac{3}{y} + y^2
Correct Answer: A

Solution:

A polynomial is an algebraic expression in which the exponents of the variable are whole numbers. The expression 3x2+5x+73x^2 + 5x + 7 is a polynomial because all the exponents are whole numbers.

A.

x^3 - x^2 + 4x + 7

B.

3y^2 + 5y

C.

x + 1/x

D.

t^2 + 4
Correct Answer: C

Solution:

The expression x+1/xx + 1/x is not a polynomial because it includes x1x^{-1}, which is not a whole number exponent.

A.

x - 1

B.

x + 1

C.

x - 2

D.

x + 2
Correct Answer: A

Solution:

By trial, we find that p(1) = 0, so x - 1 is a factor of the polynomial.

A.

y1y - 1

B.

y2y - 2

C.

y3y - 3

D.

y+1y + 1
Correct Answer: B

Solution:

The polynomial y25y+6y^2 - 5y + 6 can be factored as (y2)(y3)(y - 2)(y - 3). Therefore, both y2y - 2 and y3y - 3 are factors. Hence, option_b is correct.

A.

(y - 1)(y - 3)

B.

(y + 1)(y - 3)

C.

(y - 2)(y - 1)

D.

(y - 3)(y + 2)
Correct Answer: A

Solution:

The polynomial q(y)=y24y+3q(y) = y^2 - 4y + 3 can be factorized by finding two numbers that multiply to 3 and add to -4. These numbers are -1 and -3, so q(y)=(y1)(y3)q(y) = (y - 1)(y - 3).

A.

5x+255x + 25

B.

10x+2510x + 25

C.

2525

D.

x2+10x+25x^2 + 10x + 25
Correct Answer: A

Solution:

The original area is x2x^2. The new area is (x+5)2=x2+10x+25(x + 5)^2 = x^2 + 10x + 25. The increase in area is (x2+10x+25)x2=10x+25(x^2 + 10x + 25) - x^2 = 10x + 25.

A.

Yes, because q(3)=0q(3) = 0

B.

No, because q(3)0q(3) \neq 0

C.

Yes, because q(3)=27q(3) = 27

D.

No, because q(3)=27q(3) = -27
Correct Answer: A

Solution:

Using the Factor Theorem, if t3t - 3 is a factor, then q(3)q(3) should be zero. Calculating q(3)q(3) gives 339(3)2+27(3)27=2781+8127=03^3 - 9(3)^2 + 27(3) - 27 = 27 - 81 + 81 - 27 = 0. Thus, t3t - 3 is a factor.

A.

28 units

B.

21 units

C.

14 units

D.

35 units
Correct Answer: A

Solution:

The perimeter of a square is given by 4 times the side length. So, 4 x 7 = 28 units.

A.

33 units

B.

66 units

C.

99 units

D.

1212 units
Correct Answer: D

Solution:

The original perimeter is 4x4x. The new perimeter is 4(x+3)=4x+124(x + 3) = 4x + 12. Thus, the increase in perimeter is 1212 units.

A.

4

B.

-1

C.

7

D.

-2
Correct Answer: A

Solution:

The coefficient of x2x^2 in the polynomial x3+4x2+7x2-x^3 + 4x^2 + 7x - 2 is 4.

A.

4x4x units

B.

x2x^2 units

C.

2x2x units

D.

xx units
Correct Answer: A

Solution:

The perimeter of a square is the sum of the lengths of its four sides. Therefore, if each side is xx units, the perimeter is 4x4x units.

A.

9

B.

-5

C.

1

D.

-4
Correct Answer: A

Solution:

The coefficient of xx is the number multiplying xx, which is 9.

A.

(x - 2)(x - 3)

B.

(x + 2)(x - 3)

C.

(x - 1)(x - 6)

D.

(x + 1)(x - 6)
Correct Answer: A

Solution:

The polynomial x^2 - 5x + 6 can be factorized as (x - 2)(x - 3) by finding two numbers that multiply to 6 and add to -5.

A.

2x^2 + 3x + 1

B.

1/x + x^2

C.

√x + 2

D.

x + 1/x
Correct Answer: A

Solution:

A polynomial has terms with non-negative integer exponents. 2x^2 + 3x + 1 fits this definition.

A.

4x + 8

B.

4x + 2

C.

4x + 4

D.

4x + 6
Correct Answer: A

Solution:

The original perimeter of the square is 4x4x. If the side length is increased by 2 units, the new side length becomes x+2x + 2. Thus, the new perimeter is 4(x+2)=4x+84(x + 2) = 4x + 8.

A.

2x+42x + 4 square units

B.

2x+22x + 2 square units

C.

4x+44x + 4 square units

D.

x2+4x+4x^2 + 4x + 4 square units
Correct Answer: A

Solution:

The original area of the square is x2x^2 and the new area is (x+2)2=x2+4x+4(x + 2)^2 = x^2 + 4x + 4. The increase in area is (x2+4x+4)x2=4x+4(x^2 + 4x + 4) - x^2 = 4x + 4 square units.

A.

x^2 + 3x + 5

B.

1/x + 3

C.

√x + 2

D.

3/y + y^2
Correct Answer: A

Solution:

A polynomial in one variable has whole number exponents. x^2 + 3x + 5 fits this definition.

A.

12 square units

B.

16 square units

C.

20 square units

D.

24 square units
Correct Answer: B

Solution:

The area of a square is calculated as the side length squared. Therefore, the area is 4 \times 4 = 16 square units.

A.

x - 1

B.

x + 2

C.

x - 3

D.

x + 1
Correct Answer: A

Solution:

By substituting x=1x = 1 into p(x)p(x), we find that p(1)=0p(1) = 0. Therefore, x1x - 1 is a factor of p(x)p(x).

A.

x3+x2+x+1x^3 + x^2 + x + 1

B.

x4+3x3+3x2+x+1x^4 + 3x^3 + 3x^2 + x + 1

C.

x25x+6x^2 - 5x + 6

D.

x323x2+142x120x^3 - 23x^2 + 142x - 120
Correct Answer: A

Solution:

By using the Factor Theorem, we substitute x=1x = -1 into each polynomial. For x3+x2+x+1x^3 + x^2 + x + 1, (1)3+(1)2+(1)+1=0(-1)^3 + (-1)^2 + (-1) + 1 = 0, indicating that (x+1)(x+1) is a factor.

True or False

Correct Answer: False

Solution:

In the polynomial x2x+7x^2 - x + 7, the coefficient of xx is -1, not 1.

Correct Answer: True

Solution:

The perimeter of a square is the sum of the lengths of its four sides. If each side is xx units, the perimeter is 4x4x units.

Correct Answer: True

Solution:

The perimeter of a square is calculated as 4 times the length of one side. Therefore, for a side of 10 units, the perimeter is 4 x 10 = 40 units.

Correct Answer: True

Solution:

The polynomial 3y2+5y+73y^2 + 5y + 7 consists of three terms: 3y23y^2, 5y5y, and 77.

Correct Answer: True

Solution:

The polynomial 3y2+5y+73y^2 + 5y + 7 consists of three terms: 3y23y^2, 5y5y, and 77.

Correct Answer: True

Solution:

A polynomial is an algebraic expression with whole number exponents. x2+2xx^2 + 2x is a polynomial in the variable xx because both terms have whole number exponents.

Correct Answer: True

Solution:

In the polynomial x3+4x2+7x2-x^3 + 4x^2 + 7x - 2, the coefficient of x2x^2 is 4.

Correct Answer: True

Solution:

In the polynomial x2x+7x^2 - x + 7, the term x-x has a coefficient of 1-1.

Correct Answer: True

Solution:

The polynomial 3y2+5y3y^2 + 5y consists of two terms: 3y23y^2 and 5y5y.

Correct Answer: False

Solution:

The expression x+3\sqrt{x} + 3 can be written as x1/2+3x^{1/2} + 3. Since the exponent 1/21/2 is not a whole number, it is not a polynomial.

Correct Answer: True

Solution:

The perimeter of a square is calculated as the sum of the lengths of its four sides. For a square with each side measuring 3 units, the perimeter is 4 \times 3 = 12 units.

Correct Answer: True

Solution:

By using the factorization process, x323x2+142x120x^3 - 23x^2 + 142x - 120 can be factorized into (x1)(x10)(x12)(x - 1)(x - 10)(x - 12).

Correct Answer: True

Solution:

The polynomial x3x2+4x+7x^3 - x^2 + 4x + 7 consists of four terms: x3x^3, x2-x^2, 4x4x, and 77.

Correct Answer: False

Solution:

The expression x+3\sqrt{x} + 3 can be written as x1/2+3x^{1/2} + 3. Since the exponent 1/21/2 is not a whole number, it is not a polynomial.

Correct Answer: True

Solution:

x2+2xx^2 + 2x is a polynomial in one variable, xx, with whole number exponents.

Correct Answer: False

Solution:

The expression 3/y+y23/y + y^2 can be rewritten as 3y1+y23y^{-1} + y^2. The exponent 1-1 is not a whole number, so the expression is not a polynomial.

Correct Answer: True

Solution:

The expression 3y2+5y3y^2 + 5y is a polynomial because it consists of terms with whole number exponents of the variable yy.

Correct Answer: True

Solution:

A polynomial is an algebraic expression that consists of terms with non-negative integer exponents. The expression x3x2+4x+7x^3 - x^2 + 4x + 7 has whole number exponents and is therefore a polynomial in xx.

Correct Answer: True

Solution:

A polynomial is an algebraic expression with whole number exponents. The expression x2x+7x^2 - x + 7 fits this definition, making it a polynomial in xx.

Correct Answer: True

Solution:

The polynomial x323x2+142x120x^3 - 23x^2 + 142x - 120 can be factorized by first finding that x1x - 1 is a factor and then further factorizing the quadratic x222x+120x^2 - 22x + 120 to get (x10)(x12)(x - 10)(x - 12).