Substituting A Given Value For A Variable

Substituting A Given Value For A Variable

Variables

Opening

Variables

Equations and inequalities may contain one or more variables. When you substitute a value for a variable in an equation or inequality, the equation or inequality becomes either true or false.

Look at the balance scale in the interactive. It shows the expression x + 5 on the left and the expression 2x + 3 on the right.

  • Substitute 5 for each x in the expressions. What happens when = 5?
    • Is the equation + 5 = 2+ 3 true?
    • Is the inequality + 5 > 2+ 3 true?
    • Is the inequality + 5 < 2+ 3 true?

INTERACTIVE: Balance Scale X

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