Question

Using graphing technology, create your own quadratic equation whose graph opens down and crosses the x-axis at two points. Use complete sentences to explain what piece of the quadratic equation causes its graph to open up or down. Approximate the coordinates of the vertex and x-intercepts of the parabola.

Answer 1

Here's one

http://www.wolframalpha.com/input/?i=-x^2-4x%2B3

Play about with the equation, put different number sand signs, see what happens to the graph.

Answer 2

Here is how to plot 2 at one and set the x,y ranges

http://www.wolframalpha.com/input/?i=plot+-x^2-4x%2B3%2C+x^2-3x%2B5%2C+x%3D-10..10%2C+y%3D-10..10