In the following example drag the points labeled "a", "h", and "k" to change the respective values in the equation y=a(x-h)2+k and see the effect of these changes in the graph.
Note: In the applet below the equation y=a(x-h)2+k is displayed as y=a(x-h)^2+k with the actual values for a, h, and k.
Do the following:
Modify h and k to find a parabola whose vertex is at the point (2,1). Does changing the value of a change the vertex?
Modify a, h, and k to find an equation of a parabola that passes through the 2 green points.
Is this the only parabola that passes through the 2 green points?