Entering y = ax2 into FX Graph gives you the following screen.
Pushing the Family of Curves button
allows you to set the start, finish and step for a family of curves.
Here we can see all the parabolas in the family: -5x2, -4x2, -3x2, -2x2, -1x2, 0x2, x2, 2x2, 3x2, 4x2, 5x2,
