Theory:

An algebraic expression is derived from the constants, variables, and algebraic operations of an integer.
Example:
$$6x$$; $$4y^2$$; $$5x+z^2$$ and $$1+y+y^2$$ are some algebraic expressions.
Suppose an algebraic expression $$a + 2$$ is generated. In this '$$a$$' is a variable, and '$$2$$' is constant, and the expression is combined by algebraic operation '$$+$$'.

Important!
• A variable can take any value. Its value is not fixed at all.
• A constant has a fixed value for it.
• Operations on algebraic expressions such as addition, subtraction, multiplication, division etc.