Definitions
Using Letters to Represent Numbers
1. In algebra, we use letters (e.g. x, y, z, a, b, …) to represent numbers.
For example, there are n apples in a bag.
If there are 5 bags, then the total number of apples is 5 x n.
5 x n can be any whole number value (5, 10, 15, ...), depending on the value of n.
Here, n is called the variable and 5 x n is called the algebraic expression.
2. A variable is a letter that is used to represent some unknown numbers/quantity.
E.g. x, y, z, a, b, ... are variables.
3. An algebraic expression is a collection of terms connected by the signs "+, -, ÷ and ×".
Algebraic Notations
1. We use the signs "+, −, × and ÷" in Algebra the same way as in Arithmetic.
2. We also use the same index notation as in Arithmetic.
1. To evaluate an algebraic expression, we substitute a number for the variable and carry out the computation.
2. A formula is a general mathematical statement or rule.
