In this lesson, you will learn how to determine the reasonableness of the domain and range of quadratic functions given a real world example.
If the domain and range of a quadratic function is not reasonable given a problem situation, then it may have restrictions. Use the process chart below as a guide for determining the restricted domain and range of a quadratic function given a real-world example. Click on each step to see an algorithm to check for restrictions.
A bird is building a nest in a tree 36 feet above the ground. The bird dropped a stick from the nest. The function f(x) = -16x2 + 36 describes the height of the stick in feet after x seconds. Identify the domain and range of the function.
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The variable x represents the number of seconds after the stick is dropped from the nest.
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The bird drops the stick at 36 feet.
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The point (-1, 20) means at -1 second the stick is 20 feet above the ground. The point (2, -28) means at 2 seconds the stick is 28 feet below the ground.
Click on each step to see the process in determining the restrictions for this problem.
Does your answer make sense for this specific problem? Why or why not?
Interactive popup. Assistance may be required. It does not make sense to include negative numbers within the domain because time cannot be negative. In addition, it does not make sense to include negative numbers within the range because the height of the stick does not extend below ground level.