**Creating an algebraic activity with GeoGebra, 3.2.**

We will work on creating an activity along the lines of the one at file:///Users/mikemay/Desktop/JMMGeoGebra/GeoGebraFiles/QuadEqn.html.

We start with a clean GeoGebra window and select the slider tool.

Each slider should have a range from -10 to 10.

Using the slider tab we give it a vertical orientation and a width of 300.

There is also an animation tab, which we will ignore for the time being.

Once the sliders have been created (and perhaps moved to a good position) we create a function in the input bar defining f(x)=a*x^2+b*x+c.

Now we can change the values of the sliders and see how that changes the graph.

We also close the algebra window to give more room in the graph.

Depending on your operating system, you can either right-click or control-click on a slider to start animation of the slider.

Once animation is started there is a run/pause button in the lower right corner to control animation. You can also go to the properties of the number to change the settings for the slider.

The real lesson of this handout is adding text to make the tool more useful to the students.

We want to have a text that includes a preset formula and also includes the value of the quadratic equation with the parameters filled in. We combine LaTeX strings in quotes with values of GeoGebra objects.

We similarly produce texts to give the roots of the equation and then the equation in factored form.

The equation is simpler if we first define Root1=(-b+sqrt(b^2-4*a*c))/(2*a) and

Root2=(-b-sqrt(b^2-4*a*c))/(2*a)

We can add in information putting the quadratic equation in other forms.

© 2011, Mike May, S.J.

## Except where otherwise **noted**, content on this site is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license, Mike May, S.J. maymk@slu.edu

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