What is a mathematical model? Explain in your own words. What are some ...

(a) Describe in your own words how to graph a parabola. How do you know if the parabola opens upward or downward? Demonstrate with an example. (b) What is the vertex of a parabola? How do you determine the vertex of the parabola? Demonstrate with an example. 

What is a mathematical model? Explain in your own words. What are some examples of mathematical models that we can use when working with quadratic functions?