Transformations with Parabolas

This applet allows you to view transformations on the graph of [math]y=x^2[/math] using sliders. [math]y=x^2[/math] is the original function. By moving the sliders inside the green box, you will get a new graph that is the result of transformations on the graph of [math]y=x^2[/math]. Please play around with the sliders to see how they affect the graph. The shadow of the original function will remain fixed. The equation of the new graph is shown at the top of the green box. To get back to the original graph set h = k = 0 and a = 1.

Please play around with the sliders. Notice how they affect the graph. Of the three, which one affects whether the parabola opens up or down? The parabola opens up when a is __________. The parabola opens down when a is ____________. Of the three parameters, which one(s) affect the vertex? Express the vertex in terms of the variables a, h and/or k.