# Algebraic expression Term and basic formula

## VARIABLES OR LITERALS:

A symbol which takes on various numerical values is known as a variable or a literal.

We know that the perimeter of a square of side a is given by the formula, P = 4a.

Here 4 is a constant, while a and P are variables.

### Constants:

A symbol having a fixed numerical value is called a constant.

e.g. 7, - 2, etc. are all constants.

### FUNCTION:

Any expression involving a letter is called a function of that letter.

2a  5b + 6c – 7c + 8xd

e.g. x2 + 3x + 2 is a function of x.

### ALGEBRAIC EXPRESSIONS :

A combination of constants and variables, connected by +, - , x  and ÷ is known as an algebraic expression.

e.g. (i) 6a + 7b is an expression containing 2 terms, namely 6a and 7b.

(ii) 7 + 5x – 8xy is an expression containing 3 terms, namely 7, 5x and – 8xy.

### MONOMIALS:

An algebraic expression containing one term only, is called a monomial.

e.g. 5x, 6y2, 3x2 yz, - 9 are all monomials.

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