Chapter 2 Polynomials Notes for Class 9th Math

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CHAPTER – 2 POLYNOMIAL

  1. Polynomials in one Variable
  2. Zeroes of a Polynomial
  3. Remainder Theorem
  4. Factorisation of Polynomials
  5. Algebraic Identities
  • Constants: A symbol having a fixed numerical value is called a constant.
  • Variables: A symbol which may be assigned different numerical values is known as variable.
  • Algebraic expressions: A combination of constants and variables. Connected by some or all of the operations +, -, X and is known as algebraic expression.
  • Terms: The several parts of an algebraic expression separated by ‘+’ or ‘-‘ operations are called the terms of the expression.
  • Polynomials: An algebraic expression in which the variables involved have only nonnegative integral powers is called a polynomial.
  1. 5x2 – 4x2 – 6x – 3 is a polynomial in variable x.

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  1. (ii) 5 + 8x2 + 4x-2 is an expression but not a polynomial.

Polynomials are denoted by p(x), q(x) and r(x)etc.

  • Coefficients: In the polynomial x3 + 3x2 + 3x +1, coefficient of x3, x2, x are1,3,3 respectively

and we also say that +1 is the constant term in it.

  • Degree of a polynomial in one variable: In case of a polynomial in one variable the highest

power of the variable is called the degree of the polynomial.

  • Classification of polynomials on the basis of degree.

Degree Polynomial Example

  1. 1 Linear x +1, 2x + 3etc.
  2. 2 Quadratic ax2 + bx + c etc.
  3. 3 Cubic x3 + 3x2 +1 etc. etc.
  4. 4 Biquadratic x4 -1
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Classification of polynomials on the basis of no. of terms

Polynomial & Examples. Monomial – S3Sx31Yetc.

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No. of terms

(i) 1

Binomial – (3 + 6x), (x – 5y) etc.

(ii) 2

(iii) 3

Trinomial- 2x2 + 4x + 2 etc. etc.

  • Constant polynomial: A polynomial containing one term only, consisting a constant term is called a constant polynomial the degree of non-zero constant polynomial is zero.
  • Zero polynomial: A polynomial consisting of one term, namely zero only is called a zero polynomial. The degree of zero polynomial is not defined.
  • Zeroes of a polynomial: Let p(x) be a polynomial. If p(a) =0, then we say that is a zero of the polynomial of p(x).
  • Remark: Finding the zeroes of polynomial p(x) means solving the equation p(x)=0.
  • Remainder theorem: Let f (x) be a polynomial of degree n > I and let a be any real

number. When f(x) is divided by (x – a) then the remainder is f (a)

  • Factor theorem: Let f(x) be a polynomial of degree n > 1 and let a be any real number.
  1. If f (a) = 0 then (x – a) is factor of f (x)
  2. If (x – a) is factor of f (x)then f (a) = 0
  • Factor: A polynomial p(x) is called factor of q(x) divides q(x) exactly.
  • Factorization: To express a given polynomial as the product of polynomials each of degree less than that of the given polynomial such that no such a factor has a factor of lower degree, is called factorization.

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