U N I T 5 S E C T 4 W R I T I N G A F U N C T I O N R U L E

9

Click here to load reader

Transcript of U N I T 5 S E C T 4 W R I T I N G A F U N C T I O N R U L E

Page 1: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

WRITING

A

FUNCTION

RULE

Page 2: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

24

13

02

-11

f(X)XStart out by asking yourself, “How do I get from 1 to -1?”

How do I get from 2 to 0?

How do I get from 3 to 1?

How do I get from 4 to 2?

f(x) = X – 2

-2

-2

-2

-2

Page 3: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

84

63

42

21

YX Ask yourself, “How can I get from 1 to 2?

How can I get from 2 to 4?

How can I get from 3 to 6?

How can I get from 4 to 8?

Which one makes the rule?

Y = 2X

+1 or 2(1)

+2 or 2(2)

+3 or 2(3)

+4 or 2(4)

Page 4: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

97

86

75

64

53

42

31

YXHow do I get from 1 to 3?

How do I get from 2 to 4?

How do I get from 3 to 5?

How do I get from 4 to 6?

Y = X + 2

+2

+2

+2

+2

Page 5: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

63

41

2-1

0-3

f(x)X How do you get from -3 to 0?

How do you get from -1 to 2?

How do you get from 1 to 4?

How do you get from 3 to 6?

f(x) = x + 3

+3

+3

+3

+3

Page 6: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

00

-1-2

-2-4

-3-6

-4-8

f(x)X How do you get from -8 to -4?

How do you get from -6 to -3?

How do you get from -4 to -2?

How do you get from -2 to -1?

Which one makes the rule?

f(x) = x/2

Does this hold true for 0?

/2 or +4

/2 or + 3

/2 or +2

/2 or +1

Page 7: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

REAL WORLD PROBLEM SOLVING

A carpenter buys finishing nails by the pound. Each pound of nails costs $1.l9. Write a function rule to describe this relationship.

Let x = the number of pounds of nails

Let C(x) = the cost of x pounds of nails

4.764

3.573

2.382

1.191

C(x)X C(x) = 1.19x

How much would 12 lb of finishing nails cost?

C(12) = 1.19(12)

C(12) = 14.28

Page 8: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

Suppose you buy a word-processing software package for $199. You charge $15 per hour for word processing. Write a rule to describe your profit as a function of the number of hours you work.

Let n = number of hours you work

Let p(n) = the profit you will make

Think:

Total is $15 times hours minus cost of

Profit worked program

P(n) = 15n – 199

Page 9: U N I T 5    S E C T 4    W R I T I N G  A  F U N C T I O N  R U L E

THE END