OK, let's try one last example using a new function. A friend throws a rock straight up in the air and finds her equation to be.

h(t) = -16t ² + 72.5t + 3.6.

She evaluates her function as follows:
h(1) = -16(1)² + 72.5(1) + 3.6
h(1) = -16+ 72.5 + 3.6
h(1) = 60.1

Explain what the ordered pair (1, 60.1) means in terms of your friend's rock.

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Check Your Answer

One second after she releases her ball, it is 60.1 feet above the ground.

Now you try. How far above the ground will her rock be at t = 3.1 seconds?

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Check Your Answer

By evaluating h(3.1) = -16(3.1)² + 72.5(3.1) + 3.6, you find the rock will be approximately 74.6 feet above the ground. Here is a graph of h(t) = -16t² + 72.5t + 3.6 with the ordered pair (3.1, 74.6) marked in red to help you visualize the event.