On this page, you will find Algebraic Expressions and Identities Class 8 Notes Maths Chapter 9 Pdf free download. CBSE NCERT Class 8 Maths Notes Chapter 9 Algebraic Expressions and Identities will seemingly help them to revise the important concepts in less time.
CBSE Class 8 Maths Chapter 9 Notes Algebraic Expressions and Identities
Algebraic Expressions and Identities Class 8 Notes Conceptual Facts
1. Algebraic Expression: A combination of numbers which includes literal number connected by the
symbols +, -, x and + is called an algebraic expression.
For example: 5x, 8x -3, 2x + 3y, \(\frac{3}{4}\)x2 4xyz are some algebraic expressions.
Here. 5, 8, 3, 2. and 4 are constants and the literal numbers are x, y and z.
The different parts of the expression are called terms.
5x, 8x, 2x, 3y, \(\frac{3 x^{2}}{4}\) etc., are all the terms.
2. Coefficient: A coefficient is a multiplicative factor in some term of a polynomial. It is usually a number,
but may be only expression along.
For example in 7x2 – 3xy + y + 3. The first three terms respectively have coefficient 7, -3 and 3 is a
constant in given polynomial.
3. Monomial: The expression having only one term is called monomial.
For example: 3x, 8xy, 6×2, 11xyz, etc.
4. Binomial: The expression containing two terms is called binomial.
Forexample: 2x +y,x +y, 3xy-5z, \(\frac{1}{2}\) xy + 5, etc.
5. Trinomial: The expression containing three terms is called trinomial.
For example: x + 2y + 3, xy – z +\(\frac{1}{2}\) , \(\frac{1}{2}\) x2+ 2x + 5, etc.
6. Polynomial: Algebraic expression containing one or more terms with non-zero coefficient is called a
polynomial.
For example: 2+3x, x+y+3z-5, \(\frac{1}{2}\) x2+yz -5, etc.
7. Like and Unlike Terms: Algebraic expressions having same combination of literal numbers are called
like terms.
For example: 4xy, -5xy, –\(\frac{17}{3}\) xy, are like terms.
8. Algebraic expressions having different combinations of literal numbers are called unlike terms.
For example: (xy, yz, zx), (2x2, – 5xy2, 7xyz), (3, – 5x, 7yz) etc.
9. Degree of Algebraic Expression: Highest power of the variable of an algebraic expression is called its degree.
For example: Degree of 3x2 – 7x + 5 is 2.
Addition or Subtraction of two or more polynomials:
- Collect the like terms together.
- Find the sum or difference of the numerical coefficients of these terms.
For example:
(i) Add: 2x2y3, -5x2y3 + \(\frac{11}{2}\)x2yz
Answer:
(ii) Subtract: (3x – 5) from (8x – 25)
Answer:
[Arrange the terms columnwise and change the sign of and add]
Multiplication Rule of Signs:
(+x) x (+y) = (+xy)
(+x) x (-y) = (-xy)
(-x) x (y) = (-xy)
(-x) x (-y) = (+xy)