If f(x) = x², what are the vertex and the three basic points of the graphs of f(x- 1.25), f(x) - .85, .5 f(x) and .5 f(x- 1.25) + .85. Quickly sketch each graph.

At clock times 29.4, 44.1, 58.8 and 73.5 sec, we observe water depths of 10, -5.4, -13.5 and -14.3 cm.

• At what average rate does the depth change during each time interval?

Sketch a graph of depth vs. clock time.

• Use a sketch to explain why the slope of this graph between 29.4 and 44.1 sec represents the average rate at which depth changes during this time interval.