Students determine an appropriate domain and range for a function's graph and when given a quadratic function in a context, recognize restrictions on the domain.
Lesson 10 Summary
When interpreting quadratic functions and their graphs, it is important to note that the graph does not necessarily depict the path of an object. In the case of free-falling objects, for example, it is height with respect to time.
The y-intercept can represent the initial value of the function given the context, and the vertex represents the highest (if a maximum) or the lowest (if a minimum) value.
Dolphins Jumping In and Out of the Water
Watch the following video clip of the dolphins jumping in and out of the ocean.
In a study of the activities of dolphins, a marine biologist made a 24-second video of a dolphin swimming and jumping in the ocean with a specially equipped camera that recorded one dolphin’s position with respect to time. This graph represents a piecewise function, f(t), that is defined by quadratic functions on each interval. It relates the dolphin’s vertical distance from the surface of the water, in feet, to the time from the start of the video, in seconds. Use the graph to answer the questions below.
What happens at f(t) = 0?
What does f(t) = 0.50 means?
How long was Flipper under the water?
What was the maximum height Flipper reached?
How long was Flipper above the water?
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