Unit V blog post

The difference quotient is the ratio of the change in y-values over the change in x-values. It's simply a more complex variation of the formula for slope. Using Secant line and tangent line. 

A and B are points on the graph of f. A line passing trough the two points A ( x , f(x)) and B(x+h , f(x+h)) is called a secant line.

The slope of the parabola at the point (2,4). As you see in the picture the graph will be y=x^2 with a tangent line at (2,4)