Explore algebraic equivalence with the following investigation.

- Enter the expression
**2***x* into the red pan, and enter the expression *x* + 4 into the blue pan. - Enter the value
*x* = -5 into the box near the top. What happens? Change the value of *x* to 0 and then to 5. How does this change the relationship between the pans? - Find a value of
*x* such that the red pan equals 0. Where is the red dot when the red pan has a value of 0? - Find a value of
*x* such that the blue pan equals 0. Where is the blue dot when the blue pan has a value of 0? - Move the slider to adjust the value of
*x*. For what value of *x* do the red and blue pans have equal values? What happens in the graph when the values of the pans are equal? - What other observations can you make about the relationship between the values of the pans and the graph?