Algebraic Expressions Summary Class 7 NCERT Summary Chapter 10

Introduction

• Algebraic expression is formed from variables and constants using different operations.
• Symbols which are used to represent or replace numbers. They are denoted as x,y,z,a,b,c.... and can take different numerical values. We generally use small letters to represent variables.
• The parts of an expression which are formed separately first and then added are known as terms. Terms are added to form expressions.
• Coefficient is the numerical factor in a term. Sometimes, any factor in a term is called the coefficient of the remaining part of the term.
• The terms having the same algebraic factors are called like terms. 
• The terms having different algebraic factors are called unlike terms

Types of Algebraic Expressions

• Expression with one term is called a Monomial.
• Expression with two unlike terms is called a Binomial.
• Expression with three unlike terms is called a Trinomial.
• In general, an expression with one or more than one term is called a ‘Polynomial’. Thus a monomial, a binomial and a trinomial are all polynomials.

Addition and Subtraction of Algebraic Expressions

• The sum of two like terms is a like term with coefficient equal to the sum of coefficients of the two like terms.
• When we add two algebraic expressions, the like terms are added and the unlike terms are written as they are.
• The difference of two like terms is a like term with coefficient equal to the difference of coefficients of the two like terms.
• When we subtract two algebraic expressions, the like terms are subtracted and the unlike terms are written as they are.