Increasing and Decreasing
Best opened with Google Chrome. Type "Cntrl" + "-" to shrink the app to fit your screen. Type in the function of your choice. Chose a value (x_0) to draw the tangent line. Next, choose a range to view the tangent line move. Use the red slider to move the tangent line. The trace option highlights the graph red when it is decreasing and green when it is increasing. The tangent line turns blue when its horizontal and orange when it is vertical/undefined.