SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
Do Now:
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1)​ ​ Write the equation of the line on the graph below: ​
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2)​ ​
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Write the equation of the line that passes through the points (-9, 1) and (1, -19)​ ​
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
Real-World Applications of the Slope-Intercept Form ​
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Example: ​
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1)​ ​ The cost of food for a dinner is $300 plus $10 per student. The cost of the food as a function ​
of the number of students is shown on the ​
graph. ​
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C omplete the following questions. ​
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a)​ ​ What type of function is the graph? ​
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b)​ ​ What is the independent variable? ​
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c)​ ​ What is the dependent variable? ​
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d)​ ​ What is the slope and what does the slope ​
represent in the context above? ​
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e)​ ​ Where is the ​y-​ intercept on the graph? What does the ​y-​ intercept represent in the context of ​
the problem? ​
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f)​ ​ Write a function rule that represents the cost of the dinner as a function of the number of ​
students. ​
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g)​ ​ Find the cost for 50 students to attend this dinner. ​
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
2) Laura is on a two-day hike in the Smoky Mountains. She hiked 8 miles on the first day. Her
total distance as a function of time for the second day is shown on the graph.
a) What type of function is the graph?
b) What is the independent variable?
c) What is the dependent variable?
d) At what rate of speed is she hiking?
e) What is the slope of this line?
f) What does the slope represent in the context above?
g) What is the y-intercept of this line?_________ Where is this on the graph?_____________
h)
What does the y-intercept represent in the context of the problem?
i) Write a function rule that represents the distance that Laura traveled as a function of the
number of hours she hiked on the second day.
j) What will be Laura’s total distance if she hiked for 6 hours on the second day?
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
Quick C heck for Undestanding
3) A caterer charges a $200 fee plus $18 per person served. The total cost of the catering fees
as a function of the number of guests is shown in the graph
at right.
a) Write a function rule for the total cost of the catering.
b) Identify the slope and the y-intercept in this equation and
describe their meanings.
c) If you have $4,000, can you have an event for 200 guests?
Explain.
4) A closet organizer charges $100 initial consultation fee plus $30 per hour. The cost as a
function of the number of hours worked is graphed below.
a) Write a function rule for the total cost of the organizers
fee as a function of the number of hours worked.
b) Identify the slope and the y-intercept and describe their
meanings.
c) Find the cost if the organizer works 12 hours.
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
Summary:
​ ​ The e
​ quation of a line ​ tells the relationship between the ​x-​ values and the y​ -​ values in a ​
linear function. ​
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​ ​ A point is ​on the graph of a line ​ if it makes the equation of the line true. ​
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Exit Ticket
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1)​ ​ What is the slope of the line? ​
a)​ ​ 24 ​
b)​ ​ 35 ​
c)​ ​ 50 ​
d)​ ​ 70 ​
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2)​ ​ What does the slope represent? ​
a)​ ​ The enrollment fee ​
b)​ ​ The late payment fee ​
c)​ ​ The total cost of membership ​
d)​ ​ The monthly membership fee ​
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3)​ ​ ​
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
LESSON PRACTICE
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SWBAT: Writing Equations for Real Life Situations.
Lesson 7-4
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