Page 732 - Basic College Mathematics with Early Integers

708 A PPEND I X B I EXPONENTS AND POLYNOMIALS

Many real-world applications are modeled by polynomials.

PRACTICE 11 Example 11 Finding the Height of an Object
An object is dropped from the
top of a 530-foot cliff. Its height An object is dropped from the top of an 800-foot-tall building. Its height at time
2
in feet at time t seconds is given t seconds is given by the polynomial -16t + 800. Find the height of the object
2
by the polynomial -16t + 530. when t = 1 second and when t = 3 seconds.
Find the height of the object
when t = 1 second and when
t = 4 seconds.

800 feet

Solution: To find each height, we evaluate the polynomial when t = 1 and when
t = 3.
2
2
-16t + 800 =-16112 + 800
=-16 + 800
= 784
Don’t forget to insert The height of the object at 1 second is 784 feet.
units, if appropriate. -16t + 800 =-16132 + 800
2
2
=-16192 + 800
=-144 + 800
= 656

t 1
t 3

800
feet
784
feet
656
feet

Copyright 2012 Pearson Education, Inc.

The height of the object at 3 seconds is 656 feet.
Work Practice 11

Answer
11. 514 feet; 274 feet