Writing and Evaluating Expressions
Standard
7.P.2 Evaluate simple algebraic expressions for given variable values, e.g., 3a2 – b for a = 3 and b = 7.
Cluster
C14
Vocabulary
Evaluate-solve
Objective
To evaluate variable expressions
To solve problems by evaluating expressions
Lesson
Solving if they give you the value of the variable
If x=3, the expression 7x + 4 becomes 7 * 3 + 4 which is equal to 21 + 4 or 25. To evaluate an expression with a variable, simply substitute the value of the variable into the expression and simplify.
Replacing more than one variable
If x=3, and y=5, the expression 7x + y - 4 becomes 7 * 3 +5 - 4 which is equal to 21 + 5 - 4 or 22. To evaluate an expression with two or more variables, substitute the value of the variables into the expression and simplify.
