1. 4.6 Formalizing relations and functions
To determine whether a relation is a function AND to find the domain and range using function notation.
Day 3

2. You can read 2000 words in 8 minutes.
Evaluating a function
The function w(x) = 250x represents the number of words w(x) you can read in x minutes. How many words can you read in 8 min?
w(x) = 250x
w( ) = 250( )
w(x) = 250x 8 8
w( 8 ) = 2000
What does w(8) = 2000 mean?
You can read 2000 words in 8 minutes.

3. 0 < q < 3 q 3 0 < A(q) < 300 A(q) A(0) = 100(0)
You have 3 qt of paint to paint the trim in your home. A quart of paint covers 100ft2. The function A(q) = 100q represent the area A(q), in square feet, that q quarts of paint cover. What domain and range are reasonable for the function? What is the graph of the function?
KNOW NEED PLAN
Have 3 qt of paint
Reasonable domain and range values
Find least and greatest amounts of paint. Make a graph.
1 qt covers 100ft2
Domain:
variable?
Smallest amount? Largest amount?
0 < q < 3 q 3
Range:
variable?
Smallest amount? Largest amount?
0 < A(q) < 300
A(q)
A(0) = 100(0)
A(3) = 100(3)
A(0) = 0
A(3) = 300
Paint usage q
A(q) 1 2 3
300
200
100
Area
page 271: , 22, 24-27,31-35,41
100
200
300
Paint used (qt) q