Variable: A symbol which takes various numerical values is called a variable.
The perimeter P of a rectangle of sides l and b is given by P = 2 (l + b). Here, 2 is a constant and l and b are variables.
Algebraic Expressions: A combination of constants and variables with four fundamental operations of addition, subtraction, multiplication and division is called an algebraic expression.
Terms: Various parts of an algebraic expression which are separated by the signs of + or – are called the ‘terms’ of the expression.
Ex. 2x2 – 3xy + 5y2 is an algebraic expression consisting of three terms, namely, 2x2,–3xy and 5y2.
Kinds of algebraic expression:
Monomial : An algebraic expression containing only one term is called a monomial.
Ex. – 5, 3y, 7xy, 3/2 x2yz, etc. are all monomials.
Binomial : An algebraic expression containing two terms is called a binomial.
Ex. The expression 2x – 3, 3x + 2y, xyz –5 etc. are all binomials.
Trinomial: An algebraic expression containing three terms is called a trinomial.
Ex. The expressions a – b + c , 2x2 + y2 – xy, etc. are trinomial.
Factors of term: Each terms in an algebraic expression is a product of constant and variable . These number(s) and variables are known as the factors of those terms.
A constant factor is called a numerical factor, while a variable factor is known as a literal factor.
Class 8 Algebraic Expressions and Identities - 2
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