3/25/2014
In this lesson you will learn how
to interpret the rate of change
and the y-intercept in context by
examining each of the four
representations.
You can access a video that goes
with these notes by going to:
Learnzillion.com
And searching for the following
code: LZ1837
Let’s Review
Let’s
Review
The table shows
the late fees a
movie rental
company
charges.
Initial value
(y-intercept)
x
(days
late)
y
(late
fees)
1
$0.50
2
$1.00
1
3
$1.50
4
$2.00
0.50
=0
Rate of change =
(slope)
0.50
1
=0.50
What does the y-intercept mean?
What does the y-intercept mean?
The late fee when the number of
days
late is 0
What does the slope mean?
What does the slope mean?
The late fee increases $0.50 per day
A pool is being emptied. The
equation to model the remaining
water (W) at time (t) is W = 1400 –
350t
W = -350T + 1400
Lesson
A 1400 gallon pool is being
emptied at a rate of 350 gallons
per hour.
Core
Let’s
Review
T
(hours)
Identify and Interpret the slope
and y-intercept
100
W
(remaini
ng
gallons)
0
1400
1
1050
2
700
3
350
1
3/25/2014
T
(hours)
From the graph:
The y-intercept is (0,
1400)
100
The slope is:
700 − 1400
−700
=−
2−0
2
= −350
1
W
(remaini
ng
gallons)
0
1400
1
1050
2
700
3
350
-350
From the table:
y-intercept (𝑡 = 0) is (0, 1400)
Slope is
What does the y-intercept mean?
What does the slope mean?
−350
1
What does the y-intercept mean?
The initial amount of water in the
pool
What does the slope mean?
The amount of water in the pool
is decreasing 350 gallons per hour
Identify the slope and
y-intercept in each
Practice
representation.
Explain the meaning of
A car rental agency each.
charges $30 plus
$0.25 per mile for
each mile driven.
Guided
Let’s
Review
In this lesson you have
learned how to interpret
the rate of change and
the y-intercept in context
by examining each of the
four representations.
m
C
(miles) (cost)
0
$30
4
$31
8
$32
12
$33
C = 30 + 0.25m
2
3/25/2014
What is the y-intercept and what does it mean?
What is the slope and what does it mean?
Quick
Let’s
Review
Quiz
A restaurant charges $150 for a
room and $10 per person for food
and drinks. What is the slope and
what does it mean in the context of
the scenario?
a) Total increases $10 for the room cost.
b) Total increases $10 for every added
person
c) Total is $150 for the room cost.
d) Total is $150 for every added person.
Quick
Let’s
Review
Quiz
A restaurant charges $150 for a room
and $10 per person for food and
drinks. What is the y-intercept and
what does it mean in the context of the
scenario?
a) Total is $10 with zero people attending.
b) Total increases $10 for every added
person
c) Total is $150 with zero people attending.
d) Total is $150 for every added person.
3