Get more lessons like this at http://www.MathTutorDVD.com In this lesson, you will learn what an algebraic expression is and why they are important in algebra. Algebraic expressions are evaluated by substituting the value of the variable in the expression then simplifying the result. This is used when solving equations, inequalities, radicals, graphing and more. Simplifying algebraic expressions is a core concept in algebra that is used in almost every skill.