NCERT Class 8 Mathematics Chapter 9 Algebraic Expressions and Identities CBSE Board Sample Problems

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Algebraic Expressions and Identities

Algebraic Expressions is the expression having constants and variable. It can have multiple variable and multiple power of the variable

Example

Some Important Points on Algebraic Expressions

Some Important Points on Algebraic Expressions
Some important points on algebraic expressions

Terms

Description

Terms factors

Terms are added to form expressions terms themselves can be formed as the product of factors

Coefficient

The numerical factor of a term is called its numerical coefficient or simply coefficient

Monomial

Algebraic expression having one terms is called monomials

Example

3x

Binomial

Algebraic expression having two terms is called Binomial

Example

Trinomial

Algebraic expression having three terms is called Trinomial

Example

Polynomial

An expression containing, one or more terms with non-zero coefficient (with variables having non negative exponents) is called a polynomial

Like terms

When the variable part of the terms is same, they are called like terms

Unlike terms

When the variable part of the terms is not same, they are called like terms

Operation on Algebraic Expressions

Operation on Algebraic Expressions
Operation on algebraic expressions

S. no

Operation

Descriptions

1.

Addition

ϖ We write each expression to be added in separate row, while doing so we write like terms one below the other

Or

We add the expression together on the same line and arrange the like term together

ϖ Add the like terms

ϖ Write the Final algebraic expression

2.

Subtraction

ϖ We write each expression to be subtracted in a separate row, while doing so we write like terms one below the other and then we change the sign of the expression which is to be subtracted i.e. +becomes-and-becomes+ or We subtract the expression together on the same line, change the sign of all the term which is to be subtracted and then arrange the like term together

ϖ Add the like terms

ϖ Write the Final algebraic expression

3.

Multiplication

  • We have to use distributive law and distribute each term of the first polynomial to every term of the second polynomial.

  • When you multiply two terms together you must multiply the coefficient (numbers) and add the exponents

  • Also as we already know ++ equals =, +-or -+ equals- and- - equals +

  • Group like terms

What is an identity?

An identity is an equality, which is true for all values of the variables in the equality.

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