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Home > AC > Chapter 2 > Lesson 2.1.7 > Problem 2-69


Sylvia simplified the expressions on the expression comparison mat shown below. Some of her work is shown. Are all of her moves “legal”? Explain. 2-69 HW eTool (CPM).

Go through your list of legal moves and check each move made by Sylvia.

Removing the same amount from both sides is a legal move.

Flipping tiles from the subtraction region to the addition region and changing it from positive to negative is a legal move.

Removing zero pairs is a legal move.

Removing a positive tile from the () region and a negative tile from the () region is not a legal move, because they do not make a zero pair.

Use the eTool below to simplify the expressions on the Expression comparison Mat.
Click the link at right for the full version of the eTool: 2-69 HW eTool.