Learning Resources

Focus E: Determining Quadratic Functions from Parabolas

Test yourself

First sketch a graph to show the given information:

The following solution uses Method 2 described in your text and in the lesson.

Substituting the coordinates of the vertex, (-2 , -3), into the transformational form we get:

Now substitute the coordinates of the second point, (4, -8), into this equation to determine the value of k:

Since the transformational form requires the reciprocal of k we have the equation: