An Algebraic Expression is the combination of constant and variables. We use the operations like addition, subtraction etc., to form an algebraic expression.
A variable does not have a fixed value .it can be varied. It is represented by letters like a, y, p, m etc.
A constant has a fixed value. Any number without a variable is a constant.
1. 2x + 7
Here we got this expression by multiplying 2 and x and then add 7 to it.
In the above expression, the variable is x and the constant is 7.
We get it by multiplying the variable y to itself.