**Important Concepts and Formulas**

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

3. An algebraic expression is a
mathematical expression which contain variables, constant and mathematical
operators such as +, –, × and ÷.

5. When terms have the same variables
and if the powers of the variables are same, then they are called like terms, else
they are unlike terms.

6. The numerical coefficient of a term
in an algebraic expression is the number by which the term is multiplied.

7. Like terms can be combined to make a
single term.

8. We can evaluate an algebraic expression for given values of the variables.