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7th Grade Math / Lesson 3: Evaluating Expressions and Identifying Equations

 Evaluating Variable Expressions What will we be learning in this unit? This unit will review some basic terms and concepts needed to continue through this math class. Today's lesson will cover evaluating variable expressions and equations.

 Evaluating Variable Expressions To evaluate a variable expression: substitute the value given for the variable(s) then follow the Order of Operations.Evaluate P = 2L + 2W when L = 2 and W = 3. Substitute    P = 2(2) + 2(3) Multiply          P = 4 + 6 Add               P = 10PracticeEvaluate J = 4 + 6H - 2M when H = 3 and M = 4

 Evaluating Variable Expressions SolutionEvaluate J = 4 + 6H - 2M when H = 3 and M = 4Substitute    J = 4 + 6(3) - 2(4)Multiply        J = 4 + 18 - 8Add              J = 22 - 8Subtract      J = 14

 Equations Equation: must have an equal sign Which of the following are equations? A. 4 - 2 = n     B. X + Y = 3C. 6 * D          D. 4 + 7 = 11

 Equations Equation: must have an equal sign Which of the following are equations? A. 4 - 2 = n     B. X + Y = 3C. 6 * D          D. 4 + 7 = 11Solution :A is.          It has an equal sign.B is.          It has an equal sign.C is not.   It does not have an equal sign.D is.         It has an equal sign.