Download Model Equations with Variables on Both Sides

Model Equations with
Variables on Both Sides
3-4
Use with Lesson 3-4
KEYWORD: MT8CA Lab3
KEY
REMEMBER
Algebra tiles
Adding or subtracting zero does not
change the value of an expression.
+
x
−
+
1
−
–x
1
–1
+ − 0
+
California
Standards
Extension of
AF4.1 Solve two-step linear
− 0
To solve an equation with the same variable on both sides
of the equal sign, you must first add or subtract to
eliminate the variable term from one side of the equation.
equations and inequalities in one variable over
the rational numbers, interpret the solution or
solutions in the context from which they arose, and
verify the reasonableness of the results.
Activity
1 Model and solve the equation x 2 2x 4.
− +
+ + − −
− −
+
+ − +
+
x 2 2x 4
+ − +
+
+ + + − −
− −
Add x to both sides.
+ +
+ +
+ +
Remove zero.
+ +
+ +
+ +
+ + + − −
− −
+ + + − − + +
− − + +
Add 4 to both sides.
+ + + − − + +
− − + +
Remove zero.
+ +
+ +
+ +
+ + +
+
+ +
Divide each side into 3 equal
groups. 31 of each side
is the solution.
2
x
Think and Discuss
1. How would you check the solution to x 2 2x 4 using algebra tiles?
2. Why must you isolate the variable terms by having them on only one side
of the equation?
Try This
Model and solve each equation.
1. x 3 x 3
128
2. 3x 3x 18
3. 6 3x 4x 8
Chapter 3 Multi-Step Equations and Inequalities
4. 3x 3x 2 x 17