Sometimes zero pairs must be added to close the rectangle. Adding zero pairs does not change the value of the original expression since they, like their name implies, equate to 0. For example, if you need to add an x tile, you MUST also add a -x tile to keep the balance of the expression. Factor 2x2+x-6 with algebra tiles by:
Building and sketching a rectangular figure representing the expression. Indicate the zero pairs you added to close the rectangle.
Identifying the side lengths of the rectangle. Remember to use negative lengths appropriately.
Writing an equation showing that the area is equal to the product of its side length factors. Check by multiplying the factors to get the original expression.