How Do You Use the Solution from an Equation to Evaluate an Expression?

How Do You Use the Solution from an Equation to Evaluate an Expression?

Note:

If 3x=21, what is 9x? To get the answer, solve the equation for the variable. Then plug that variable value into the expression and simplify to get the answer. Follow this same process anytime you need to use an equation to evaluate an expression. Watch this tutorial to see this process in action!

Keywords:

  • problem
  • solve
  • equation
  • evaluate
  • expression
  • solve by division
  • evaluate 2nd expression
  • 2 step problem

Background Tutorials

  • Evaluating Expressions

      • How Do You Evaluate an Algebraic Expression?How Do You Evaluate an Algebraic Expression?

      How Do You Evaluate an Algebraic Expression?

      Plugging variables into an expression is essential for solving many algebra problems. See how to plug in variable values by watching this tutorial.

      • What is a Variable?What is a Variable?

      What is a Variable?

      You can't do algebra without working with variables, but variables can be confusing. If you've ever wondered what variables are, then this tutorial is for you!

  • Solving Equations by Dividing

Further Exploration

  • Solving Systems of Equations

      • How Do You Solve Two Equations with Two Variables?How Do You Solve Two Equations with Two Variables?

      How Do You Solve Two Equations with Two Variables?

      Trying to solve two equations each with the same two unknown variables? Take one of the equations and solve it for one of the variables. Then plug that into the other equation and solve for the variable. Plug that value into either equation to get the value for the other variable. This tutorial will take you through this process of substitution step-by-step!

  • Solving Equations by Multiplying

  • Solving Equations by Dividing