Produce several (5 to 10) graphs of
on the same axis using different values for D.
Here are what eight graphs look like for different values of d
Notice that the term submitted for d is the x value of the vertex.
Varying D does not change the slope of the graph. The slope does not change because the coefficient in front of the first term () is not different. A varying slope will occur when this coefficient varies.
Varying D does however change the position of the graph by moving it's vertex horizontally across the y=-2 line
For more of an illustration click here (QuickTime Player)