1. Chapter 7 Section 7 Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley

2. Applications of Rational Expressions Solve problems about numbers. Solve problems about distance, rate, and time. Solve problems about work. 1 1 3 3 2 27.77.7

3. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1 Objective 1 Solve problems about numbers. Slide 7.7 - 3

4. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley A certain number is added to the numerator and subtracted from the denominator of. The number equals the reciprocal of. Find the number. EXAMPLE 1 Solving a Problem about an Unknown Number Slide 7.7 - 4 Solution: It is important to check your solution from the words of the problem because the equation may be solved correctly, but set up incorrectly.

5. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 2 Objective 2 Solve problems about distance, rate, and time. Slide 7.7 - 5

6. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Solve problems about distant rate and time. Slide 7.7 - 6 Recall the following formulas that relate distance, rate, and time.

7. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley EXAMPLE 2A Solving a Problem about Distance, Rate, and Time Slide 7.7 - 7 Solution: At the 2006 Winter Olympics, Joey Cheek of the United States won the 500-m speed skating event for men in 69.76 sec. What was his rate (to the nearest hundredth of a second)? (Source: http://en.wikipedia.org) Joey Cheek traveled at a rate of 7.17 meters per second.

8. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley In 2004, the Indianapolis 500 race was only 450 mi. Buddy Rice won with a rate of 138.518 mph. What was the time (to the nearest hundredth of an hour)? (Source: World Almanac and Book of Facts 2006) EXAMPLE 2B Solving a Problem about Distance, Rate, and Time Solution: Buddy Rice’s time was 3.25 hours. Slide 7.7 - 8

9. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley EXAMPLE 2C A boat can go 10 mi against a current in the same time it can go 30 mi with the current. The current flows at 4mph. Find the speed of the boat with no current. Solution: Solving a Problem about Distance, Rate, and Time Slide 7.7 - 9 The speed of the boat with no current equals 8 miles per hour. drt Downstream 30x+4 Upstream 10x−4

10. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 3 Objective 3 Slide 7.7 - 10 Solve problems about work.

11. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Solve problems about work. Slide 7.7 - 11 If a job can be completed in t units of time, then the rate of work is

12. Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Al and Mario operate a small roofing company. Mario can roof an average house alone in 9 hr. Al can roof a house alone in 8 hr. How long will if take them to do the job if they work together? Solution: EXAMPLE 3 Solving a Problem about Work Rates Slide 7.7 - 12 It will take Mario and Al hours if they work together.