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12.9 Conic Sections
Name the curve that is the graph of the equation and state whether or not the relation is a function.
x2 ‐ 8y2 = 16
x2 = 1 ‐ y2
y = x2 ‐ 5x 3
12.10 The Inverse Variation Hyperbola
*If x and y vary inversely, then xy = a constant.
*The value of xy is the CONSTANT OF VARATION
Examples of Inverse Variation:
As you walk faster (x), the time (y) it takes you to walk through the 8 mile park decreases. If walking at a rate of 4mph takes you 2 hours, how long would it take you to walk through the park if you rode your bike at 12mph?
The number of days (x) needed to complete a job varies inversely as the number of workers (y) assigned to the job. If the job can be completed by 2 workers in 10 days, then how many workers would it take to complete the job in 5 days?
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The cost of hiring a bus for a trip to Niagara Falls is $400. The cost per person (x) varies inversely as the number of persons (y) who will go on the trip. a) Find the cost per person if 25 people go on the trip
b) Find the number of people who are going if the cost per person is $12.50.
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Graphing Inverse Variation: First get y alone
1) xy = 20
2. xy = ‐12
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Homework: pg 538 #1‐4(a‐d), 6‐9(just a and d)
pg 542 #3, 5 (sketch the graphs from your calc), 9‐13
Quiz tomorrow on 12.7‐10
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