Polynomial Class 10 Notes: Chapter 2

CBSE Class 10 Maths Notes Polynomial:-Download PDF Here

Class 10 Maths Chapter 2 Polynomial Notes

CBSE Class 10 Maths Chapter 2 Polynomial Notes are provided here in detail. Here, we are going to discuss the complete explanation of what is polynomial and its types, algebraic expressions, degree of a polynomial expression, graphical representation of the polynomial equations, factorization, relationship between zeroes and coefficient of a polynomial, and so on with many examples.

Students can refer to the short notes and MCQ questions along with separate solution pdf of this chapter for quick revision from the links below:

  • Polynomials Short Notes
  • Polynomials MCQ Practice Questions
  • Polynomials MCQ Practice Solutions
  • Algebraic Expressions

    An algebraic expression is an expression made up of variables and constants along with mathematical operators.
    An algebraic expression is a sum of terms, which are considered to be building blocks for expressions.

    Algebraic Expression

    A term is a product of variables and constants. A term can be an algebraic expression in itself.
    Examples of a term – 3, which is just a constant.
    – 2x, which is the product of constant ‘2’ and the variable ‘x’
    – 4xy, which is the product of the constant ‘4’ and the variables ‘x’ and ‘y’.
    – 5x2y, which is the product of 5, x, x and y.

    The constant in each term is referred to as the coefficient.

    Example of an algebraic expression: 3x2y+4xy+5x+6 which is the sum of four terms: 3x2y, 4xy, 5x and 6.

    An algebraic expression can have any number of terms. The coefficient in each term can be any real number. There can be any number of variables in an algebraic expression. The exponent on the variables, however, must be rational numbers.

    To know more about Algebraic Expressions, visit here.

    Polynomial

    An algebraic expression can have exponents that are rational numbers. However, a polynomial is an algebraic expression in which the exponent on any variable is a whole number.

    Polynomials

    Let us consider a few more examples,
    5x3+3x+1 is an example of a polynomial. It is an algebraic expression as well.

    2x+3√x is an algebraic expression but not a polynomial. – since the exponent on x is 1/2, which is not a whole number.

    To know more about polynomials, visit here.

    Degree of a Polynomial

    For a polynomial in one variable – the highest exponent on the variable in a polynomial is the degree of the polynomial.

    Example: The degree of the polynomial x2+2x+3 is 2, as the highest power of x in the given expression is x2.
    Consider another example, the degree of the polynomial x8 + 2x6 – 3x + 9 is 8 since the greatest power in the given expression is 8.

    Types Of Polynomials

    Polynomials can be classified based on the following.
    a) Number of terms
    b) Degree of the polynomial.

    Types of Polynomials Based on the Number of Terms

    a) Monomial – A polynomial with just one term. Example: 2x, 6x2, 9xy

    b) Binomial – A polynomial with two unlike terms. Example: 4x2+x, 5x+4

    a) Trinomial – A polynomial with three unlike terms. Example: x2+3x+4

    Types of Polynomials based on Degree

    Linear Polynomial

    A polynomial whose degree is one is called a linear polynomial.
    For example, 2x+1 is a linear polynomial.

    Quadratic Polynomial

    A polynomial of degree two is called a quadratic polynomial.
    For example, 3x2+8x+5 is a quadratic polynomial.

    To know more about the types of polynomials, click here.

    For more information on Quadratic Polynomials, watch the below video


    Cubic Polynomial

    A polynomial of degree three is called a cubic polynomial.
    For example, 2x3+5x2+9x+15 is a cubic polynomial.

    Graphical Representations

    Let us learn here how to represent polynomial equations on the graph.

    Representing Equations on a Graph

    Any equation can be represented as a graph on the Cartesian plane, where each point on the graph represents the x and y coordinates of the point that satisfies the equation. An equation can be seen as a constraint placed on the x and y coordinates of a point, and any point that satisfies that constraint will lie on the curve.

    For example, the equation y = x, on a graph, will be a straight line that joins all the points which have their x coordinate equal to their y coordinate. Example – (1,1), (2,2) and so on.
    Polynomials for class 10 -1

    Geometrical Representation of a Linear Polynomial

    The graph of a linear polynomial is a straight line. It cuts the X-axis at exactly one point.
    Polynomials for class 10 -2

    Linear graph

    Geometrical Representation of a Quadratic Polynomial

  • The graph of a quadratic polynomial is a parabola
  • It looks like a U, which either opens upwards or opens downwards depending on the value of ‘a’ in ax2+bx+c
  • If ‘a’ is positive, then parabola opens upwards and if ‘a’ is negative then it opens downwards
  • It can cut the x-axis at 0, 1 or two points
  • Polynomials for class 10 -3

    Graph of a polynomial which cuts the x-axis in two distinct points (a>0)
    Polynomials for class 10 -4

    Graph of a Quadratic polynomial which touches the x-axis at one point (a>0)

    Polynomials for class 10 -5

    Graph of a Quadratic polynomial that doesn’t touch the x-axis (a<0)

    Graph of the Polynomial x^n

    For a polynomial of the form y=xn where n is a whole number:

  • as n increases, the graph becomes steeper or draws closer to the Y-axis
  • If n is odd, the graph lies in the first and third quadrants
  • If n is even, the graph lies in the first and second quadrants
  • The graph of y=−xn is the reflection of the graph of y=xn on the x-axis
  • Polynomials for class 10 -6

    Graph of polynomials with different degrees.

    Zeroes of a Polynomial

    A zero of a polynomial p(x) is the value of x for which the value of p(x) is 0. If k is a zero of p(x), then p(k)=0.

    For example, consider a polynomial p(x)=x2−3x+2.

    When x=1, the value of p(x) will be equal to

    p(1)=12−3×1+2

    =1−3+2

    =0

    Since p(x)=0 at x=1, we say that 1 is a zero of the polynomial x2−3x+2

    Video Lesson on Zeroes of Polynomials

    To know more about Zeroes of a Polynomial, visit here.

    Geometrical Meaning of Zeros of a Polynomial

    Geometrically, zeros of a polynomial are the points where its graph cuts the x-axis.
    Polynomials for class 10 -7

    (i) One zero (Linear Polynomial)    (ii) Two zeros (Quadratic Polynomial)    (iii) Three zeros (Cubic Polynomial)

    Here A, B and C correspond to the zeros of the polynomial represented by the graphs.

    Number of Zeros

    In general, a polynomial of degree n has at most n zeros.

    1. A linear polynomial has one zero,
    2. A quadratic polynomial has at most two zeros.
    3. A cubic polynomial has at most 3 zeros.

    Factorisation of Polynomials

    Quadratic polynomials can be factorized by splitting the middle term.

    For example, consider the polynomial 2x2−5x+3

    Splitting the middle term:

    The middle term in the polynomial 2x2−5x+3 is -5x. This must be expressed as a sum of two terms such that the product of their coefficients is equal to the product of 2 and 3 (coefficient of x2 and the constant term)

    −5 can be expressed as (−2)+(−3), as −2×−3=6=2×3

    Thus, 2x2−5x+3=2x2−2x−3x+3

    Now, identify the common factors in individual groups

    2x2−2x−3x+3=2x(x−1)−3(x−1)

    Taking (x−1) as the common factor, this can be expressed as:

    2x(x−1)−3(x−1)=(x−1)(2x−3)

    For more information on Factorisation Of Quadratic Polynomials, watch the below video


    To know more about Factorisation of Polynomials, visit here.

    Relationship between Zeroes and Coefficients of a Polynomial

    For Quadratic Polynomial:
    If α and β are the roots of a quadratic polynomial ax2+bx+c, then,

    α +  β = -b/a

    Sum of zeroes = -coefficient of x /coefficient of x2

    αβ = c/a

    Product of zeroes = constant term / coefficient of x2

    For Cubic Polynomial

    If α,β and γ are the roots of a cubic polynomial ax3+bx2+cx+d, then

    α+β+γ = -b/a

    αβ +βγ +γα = c/a

    αβγ = -d/a

    Example

    Calculate the sum of the zeroes and the product of the zeroes of the polynomial 9x2 – 16x + 20.

    Solution:

    Given polynomial: 9x2 – 16x + 20

    The given polynomial is a quadratic polynomial, as the degree of the polynomial is 2.

    We know that the standard form of a quadratic polynomial is ax2 + bx + c.

    By comparing the given polynomial and the standard form, we can write.

    a = 9

    b = -16

    c = 20

    By using the relationship between zeroes and the coefficients of the polynomial, we can get the following:

    For a quadratic polynomial,

    The sum of zeroes = -coefficient of x /coefficient of x2

    Now, substitute the values in the formula, we get

    Sum of zeroes = -(-16)/9 = 16/9.

    Similarly, Product of zeroes = constant term / coefficient of x2

    Plugging the values in the above formula, we get

    Product of zeroes = 20/9

    Hence, 16/9 and 20/9 are the sum and the product of the zeroes of the polynomial 9x2 – 16x + 20.

    To know more about Relationship between Zeroes and Coefficients of a Polynomial, visit here.

    Division Algorithm

    Let us assume that P(x) and G(x) are the two polynomials, such that G(x)≠ 0, then the division algorithm states the formula to find Q(x) and R(x) of the polynomial.

    Here, P(x) denotes dividend polynomial

    G(x) denotes divisor polynomial

    Q(x) denotes quotient polynomial

    R(x) denotes the remainder polynomial.

    Thus, the formula stated by division algorithm is:

    P(x) = G(x) × Q(x) + R(x)

    To divide one polynomial by another, follow the steps given below.

    Step 1: Arrange the terms of the dividend and the divisor in the decreasing order of their degrees.

    Step 2: To obtain the first term of the quotient, divide the highest degree term of the dividend by the highest degree term of the divisor  Then carry out the division process.

    Step 3: The remainder from the previous division becomes the dividend for the next step. Repeat this process until the degree of the remainder is less than the degree of the divisor.

    Polynomials for class 10-8

    Algebraic Identities

    1. (a+b)2=a2+2ab+b2

    2. (a−b)2=a2−2ab+b2

    3. (x+a)(x+b)=x2+(a+b)x+ab

    4. a2−b2=(a+b)(a−b)

    5. a3−b3=(a−b)(a2+ab+b2)

    6. a3+b3=(a+b)(a2−ab+b2)

    7. (a+b)3=a3+3a2b+3ab2+b3

    8. (a−b)3=a3−3a2b+3ab2−b3

    For more information on Algebraic Identities, watch the below videos



    To know more about Algebraic Identities, visit here.

    Polynomials for Class 10 Examples

    Example 1:

    Determine the quadratic polynomial, whose zeroes are 5-3√2 and 5+3√2.

    Solution:

    Given zeroes: 5-3√2 and 5+3√2.

    Finding sum of zeroes:

    Sum of zeroes = (5-3√2)+(5+3√2)

    Sum of zeroes = 5+5 = 10.

    Finding product of zeroes:

    Product of zeroes = (5-3√2)(5+3√2)

    We know that a2-b2 = (a+b)(a-b).

    Hence, (5)2– (3√2)2 = (5-3√2)(5+3√2).

    Therefore, product of zeroes = 25 – [9(2)]= 25 – 18 = 7

    Thus, the required quadratic polynomial is:

    P(x)= x2 -(sum of zeroes)x + product of zeroes

    P(x) = x2-10x+7.

    Hence, the required quadratic polynomial is x2-10x+7.

    Example 2:

    Find the zeroes of the quadratic polynomial 6x2-3-7x. Also, verify the relationship between the zeroes and the coefficient of a polynomial.

    Solution:

    Given quadratic polynomial: 6x2-3-7x.

    Let P(x) = 6x2-3-7x.

    We know that zero of a polynomial is a value of x, when P(x) = 0.

    Hence, 6x2-7x-3 = 0

    Now, factorize the above polynomial equation to find the value of x.

    Thus, 6x2-7x – 3 = 0 is also written as:

    6x2-9x+2x-3 = 0

    3x(2x-3)+1(2x-3) = 0

    (3x+1) (2x-3) =0

    Thus, 3x+1 = 0 and 2x-3 =0

    ⇒3x+1 = 0

    x = -1/3.

    Similarly,

    ⇒2x-3 = 0

    ⇒x = 3/2.

    Hence, the zeroes of the quadratic polynomial 6x2– 7x-3 are -1/3 and 3/2.

    Thus, α = -1/3 and β = 3/2 are the zeroes of the polynomial.

    Now, comparing P(x) = 6x2-7x-3 with ax2+bx+c.

    Hence, a = 6, b=-7 and c = -3.

    Verifying the Relationship Between Zeroes and Coefficient of Polynomial:

    Sum of zeroes:

    We know that the sum of zeroes = – coefficient of x/Coefficient of x2.

    Thus, α+β = -b/a

    Now, substitute the values, we get

    (-1/3)+(3/2) = -(-7)/6

    (-2+9)/6 = 7/6

    7/6 = 7/6.

    Hence, LHS = RHS.

    Product of Zeroes:

    We know that the product of zeroes = Constant term/Coefficient of x2.

    Therefore, αβ = c/a

    On substituting the values, we get

    (-1/3)(3/2) = (-3/6)

    -1/2 = -1/2

    Hence, LHS = RHS.

    Therefore, the relationship between the zeroes and coefficients of the polynomial 6x2-7x-3 is verified.

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