1 3 problems

SECTION 2.2 Graphs of Functions 167

122 Sketch the graph of the function by rst making a tableof values.

1. 2.

3. 4.

5.

6.

7. 8.

9. 10.

11. 12.

13. 14.

15. 16.

17. 18.

19. 20.

21. 22.

23. The graph of a function h is given.(a) Find , , , and .(b) Find the domain and range of h.

24. The graph of a function g is given.(a) Find , , , , and .(b) Find the domain and range of g.

x

y

0

3g

_3 3

g14 2g12 2g10 2g12 2g14 2_3 3 x

y

0

3 h

h13 2h12 2h10 2h12 2g1x 2 0 x 0

x2g1x 2 2

x2

f 1x 2 x0 x 0f 1x 2 0 2x 2 0G1x 2 0 x 0 xG1x 2 0 x 0 x H1x 2 0 x 1 0H1x 2 0 2x 0F1x 2 1

x 4F1x 2 1

x

g1x 2 1xg1x 2 1x 4 g1x 2 4x2 x4g1x 2 x3 8f 1x 2 x2 4f 1x 2 x2f 1x 2

x 32

, 0 x 5

f 1x 2 x 3, 3 x 3 f 1x 2 6 3xf 1x 2 2x 4f 1x 2 3f 1x 2 2

25. Graphs of the functions f and g are given.(a) Which is larger, or ?(b) Which is larger, or ?(c) For which values of x is ?

26. The graph of a function f is given.(a) Estimate to the nearest tenth.(b) Estimate to the nearest tenth.(c) Find all the numbers x in the domain of f for which

.

2736 A function f is given.(a) Use a graphing calculator to draw the graph of f.(b) Find the domain and range of f from the graph.27. 28.

29. 30.

31. 32.

33. 34.

35. 36.

3750 Sketch the graph of the piecewise dened function.

37. f 1x 2 e0 if x 21 if x 2

f 1x 2 1x 2f 1x 2 1x 1 f 1x 2 225 x2f 1x 2 216 x2f 1x 2 x2 4f 1x 2 4 x2 f 1x 2 x2f 1x 2 4f 1x 2 21x 1 2f 1x 2 x 1

x_2 2

2

_2

0

f

f 1x 2 1f 13 2f 10.5 2

_2 2 x

y

0

2

_2

fg

f 1x 2 g1x 2g13 2f 13 2g10 2f 10 2

2.2 Exercises

168 CHAPTER 2 Functions

38.

39.

40.

41.

42.

43.

44.

45.

46.

47.

48.

49.

50.

5152 Use a graphing device to draw the graph of the piecewise dened function. (See the margin note on page 162.)

51.

52. f 1x 2 e2x x2 if x 11x 1 2 3 if x 1f 1x 2 e x 2 if x 1

x2 if x 1

f 1x 2 cx if x 09 x2 if 0 x 3x 3 if x 3

f 1x 2 c4 if x 2x2 if 2 x 2x 6 if x 2

f 1x 2 bx2 if 0 x 0 11 if 0 x 0 1

f 1x 2 e0 if 0 x 0 23 if 0 x 0 2

f 1x 2 e1 x2 if x 2x if x 2

f 1x 2 e2 if x 1x2 if x 1

f 1x 2 c1 if x 1x if 1 x 11 if x 1

f 1x 2 c1 if x 11 if 1 x 11 if x 1

f 1x 2 e2x 3 if x 13 x if x 1

f 1x 2 e x if x 0x 1 if x 0

f 1x 2 e1 x if x 25 if x 2f 1x 2 e3 if x 2

x 1 if x 2

f 1x 2 e1 if x 1x 1 if x 1

5354 The graph of a piecewise dened function is given.Find a formula for the function in the indicated form.

5556 Determine whether the curve is the graph of a functionof x.

55.

56.

y

x0

y

x0

y

x0

y

x0

y

x0

y

x0

y

x0

y

x0

y

x0 1

2

y

x0

2

2

f 1x 2 c if x 2 if 2 x 2 if x 2

f 1x 2 c if x 1 if 1 x 2 if x 2

(a) (b)

(a) (b)

(c) (d)

(c) (d)

53.

54.


5760 Determine whether the curve is the graph of a functionx. If it is, state the domain and range of the function.

57. 58.

59. 60.

6172 Determine whether the equation denes y as a functionof x. (See Example 10.)61. x 2 2y 4 62. 3x 7y 21

63. x y 2 64.

65. x y 2 9 66. x 2 y 9

67. x 2y y 1 68.

69. 70.

71. x y3 72. x y4

7378 A family of functions is given. In parts (a) and (b) graph all the given members of the family in the viewing rectangle indicated. In part (c) state the conclusions you canmake from your graphs.

73.(a) c 0, 2, 4, 6; 35, 54 by 310, 104(b) c 0, 2, 4, 6; 35, 54 by 310, 104(c) How does the value of c affect the graph?



f 1x 2 1x c 2 3f 1x 2 1x c 2 2f 1x 2 x2 c

2x 0 y 0 02 0 x 0 y 0 1x y 12x2 1y 1 2 2 4

y

x0 2

2

y

x0 3

1

y

x0 3

2

y

x0 2

2

76.(a) ; 35, 54 by 310, 104(b) ; 35, 54 by 310, 104(c) How does the value of c affect the graph?

77.(a) ; 31, 44 by 31, 34(b) ; 33, 34 by 32, 24(c) How does the value of c affect the graph?

78.(a) n 1, 3; 33, 34 by 33, 34(b) n 2, 4; 33, 34 by 33, 34(c) How does the value of n affect the graph?

7982 Find a function whose graph is the given curve.

79. The line segment joining the points and 80. The line segment joining the points and 81. The top half of the circle x 2 y 2 9

82. The bottom half of the circle x 2 y 2 9

Applications83. Weight Function The graph gives the weight of a certain

person as a function of age. Describe in words how this persons weight has varied over time. What do you thinkhappened when this person was 30 years old?

84. Distance Function The graph gives a salesmans dis-tance from his home as a function of time on a certain day.Describe in words what the graph indicates about his travelson this day.

8 A.M. 10 NOON 2 4 6 P.M.Time (hours)

Distancefrom home

(miles)

0

150

100

50

10

200

20 30 40 50 60 70Age (years)

Weight(pounds)

16, 3 213, 2 2 14, 6 212, 1 2

f 1x 2 1/x nc 1, 13, 15c 12,

14,

16

f 1x 2 xcc 1, 1, 12, 2c 1, 12, 2, 4

f 1x 2 cx2


85. Hurdle Race Three runners compete in a 100-meter hur-dle race. The graph depicts the distance run as a function oftime for each runner. Describe in words what the graph tellsyou about this race. Who won the race? Did each runnernish the race? What do you think happened to runner B?

86. Power Consumption The gure shows the power con-sumption in San Francisco for September 19, 1996 (P ismeasured in megawatts; t is measured in hours starting atmidnight).(a) What was the power consumption at 6 A.M.? At 6 P.M.?(b) When was the power consumption the lowest?(c) When was the power consumption the highest?

87. Earthquake The graph shows the vertical acceleration of the ground from the 1994 Northridge earthquake in LosAngeles, as measured by a seismograph. (Here t representsthe time in seconds.)(a) At what time t did the earthquake rst make noticeable

movements of the earth?(b) At what time t did the earthquake seem to end?(c) At what time t was the maximum intensity of the earth-

quake reached?

(cm/s2)

Source: Calif. Dept. ofMines and Geology

5

50

5010 15 20 25

a

t (s)

100

30

P (MW)

0 181512963 t (h)21

400

600

800

200

Source: Pacic Gas & Electric

100

y (m)

0 20 t (s)

A B C

88. Utility Rates Westside Energy charges its electric customers a base rate of $6.00 per month, plus 10 per kilowatt-hour (kWh) for the rst 300 kWh used and 6 per kWh for all usage over 300 kWh. Suppose a customer uses x kWh of electricity in one month.(a) Express the monthly cost E as a function of x.(b) Graph the function E for 0 x 600.

89. Taxicab Function A taxi company charges $2.00 for therst mile (or part of a mile) and 20 cents for each succeed-ing tenth of a mile (or part). Express the cost C (in dollars)of a ride as a function of the distance x traveled (in miles)for 0 x 2, and sketch the graph of this function.

90. Postage Rates The domestic postage rate for rst-classletters weighing 12 oz or less is 37 cents for the rst ounce(or less), plus 23 cents for each additional ounce (or part ofan ounce). Express the postage P as a function of the weightx of a letter, with 0 x 12, and sketch the graph of thisfunction.

Discovery Discussion91. When Does a Graph Represent a Function? For every

integer n, the graph of the equation y xn is the graph of a function, namely . Explain why the graph of x y 2 is not the graph of a function of x. Is the graph of x y3 the graph of a function of x? If so, of what functionof x is it the graph? Determine for what integers n the graphof x yn is the graph of a function of x.

92. Step Functions In Example 8 and Exercises 89 and 90we are given functions whose graphs consist of horizontalline segments. Such functions are often called stepfunctions, because their graphs look like stairs. Give some other examples of step functions that arise in everyday life.

93. Stretched Step Functions Sketch graphs of the func-tions f(x) x, g(x) 2x, and h(x) 3x on separategraphs. How are the graphs related? If n is a positive integer,what does the graph of k(x) nx look like?

94. Graph of the Absolute Value of a Function(a) Draw the graphs of the functions

and . How are the graphs of f andg related?

(b) Draw the graphs of the functions and. How are the graphs of f and g

related?(c) In general, if , how are the graphs

of f and g related? Draw graphs to illustrate your answer.

g1x 2 0 f 1x 2 0g1x 2 0 x4 6x2 0 f 1x 2 x4 6x2

g1x 2 0 x2 x 6 0 f 1x 2 x2 x 6

f 1x 2 xn

We can describe a relation by listing all the ordered pairs in the relation orgiving the rule of correspondence. Also, since a relation consists of ordered pairswe can sketch its graph. Lets consider the following relations and try to decidewhich are functions.(a) The relation that consists of the ordered pairs .(b) The relation that consists of the ordered pairs .(c) The relation whose graph is shown to the left.(d) The relation whose input values are days in January 2005 and whose output

values are the maximum temperature in Los Angeles on that day.(e) The relation whose input values are days in January 2005 and whose output

values are the persons born in Los Angeles on that day.

The relation in part (a) is a function because each input corresponds to exactlyone output. But the relation in part (b) is not, because the input 1 corresponds to two different outputs (2 and 3). The relation in part (c) is not a function because the input 1 corresponds to two different outputs (1 and 2). The relationin (d) is a function because each day corresponds to exactly one maximum temperature. The relation in (e) is not a function because many persons (not justone) were born in Los Angeles on most days in January 2005.1. Let A 51, 2, 3, 46 and B 51, 0, 16. Is the given relation a function from

A to B?(a)(b) 5 11, 0 2 , 12, 1 2 , 13, 0 2 , 13, 1 2 , 14, 0 2 65 11, 0 2 , 12, 1 2 , 13, 0 2 , 14, 1 2 6

5 11, 2 2 , 11, 3 2 , 12, 4 2 , 13, 2 2 65 11, 1 2 , 12, 3 2 , 13, 3 2 , 14, 2 2 6


Relations and FunctionsA function f can be represented as a set of ordered pairs where x is the input and is the output. For example, the function that squares each natural number can be represented by the ordered pairs

.

A relation is any collection of ordered pairs. If we denote the ordered pairs in a relation by then the set of x-values (or inputs) is the domain and theset of y-values (or outputs) is the range. With this terminology a function is arelation where for each x-value there is exactly one y-value (or for each inputthere is exactly one output). The correspondences in the gure below are relationsthe rst is a function but the second is not because the input 7 in A corresponds to two different outputs, 15 and 17, in B.

1x, y 25 11, 1 2 , 12, 4 2 , 13, 9 2 , . . .6y f 1x 2 1x, y 2D I S C O V E R YP R O J E C T

B

Function

A

15

1817

19

B

Not a function

A

789

123

4

1020

30

y

21

1_1 2 30 x

3

2. Determine if the correspondence is a function.

3. The following data were collected from members of a college precalculusclass. Is the set of ordered pairs a function?

4. An equation in x and y denes a relation, which may or may not be a function(see page 164). Decide whether the relation consisting of all ordered pairs ofreal numbers satisfying the given condition is a function.(a) y x 2 (b) x y 2 (c) x y (d) 2x 7y 11

5. In everyday life we encounter many relations which may or may not denefunctions. For example, we match up people with their telephone number(s),baseball players with their batting averages, or married men with their wives.Does this last correspondence dene a function? In a society in which eachmarried man has exactly one wife the rule is a function. But the rule is not afunction. Which of the following everyday relations are functions?(a) x is the daughter of y (x and y are women in the United States)(b) x is taller than y (x and y are people in California)(c) x has received dental treatment from y (x and y are millionaires in the

United States)(d) x is a digit (0 to 9) on a telephone dial and y is a corresponding letter

1x, y 2

1x, y 2


(a)

(a) (b) (c)

(b)

x yHeight Weight

72 in. 180 lb60 in. 204 lb60 in. 120 lb63 in. 145 lb70 in. 184 lb

x yAge ID Number

19 82-409021 80-413340 66-829521 64-911021 20-6666

x yYear of Number of

graduation graduates

2005 22006 122007 182008 72009 1

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1 3 problems

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