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Access this online resource for additional instruction and practice with linear function models.

Key concepts

  • We can use the same problem strategies that we would use for any type of function.
  • When modeling and solving a problem, identify the variables and look for key values, including the slope and y -intercept. See [link] .
  • Draw a diagram, where appropriate. See [link] and [link] .
  • Check for reasonableness of the answer.
  • Linear models may be built by identifying or calculating the slope and using the y -intercept.
    • The x -intercept may be found by setting y = 0 , which is setting the expression m x + b equal to 0.
    • The point of intersection of a system of linear equations is the point where the x - and y -values are the same. See [link] .
    • A graph of the system may be used to identify the points where one line falls below (or above) the other line.

Section exercises

Verbal

Explain how to find the input variable in a word problem that uses a linear function.

Determine the independent variable. This is the variable upon which the output depends.

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Explain how to find the output variable in a word problem that uses a linear function.

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Explain how to interpret the initial value in a word problem that uses a linear function.

To determine the initial value, find the output when the input is equal to zero.

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Explain how to determine the slope in a word problem that uses a linear function.

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Algebraic

Find the area of a parallelogram bounded by the y -axis, the line x = 3 , the line f ( x ) = 1 + 2 x , and the line parallel to f ( x ) passing through ( 2 , 7 ) .

6 square units

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Find the area of a triangle bounded by the x -axis, the line f ( x ) = 12 1 3 x , and the line perpendicular to f ( x ) that passes through the origin.

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Find the area of a triangle bounded by the y -axis, the line f ( x ) = 9 6 7 x , and the line perpendicular to f ( x ) that passes through the origin.

20.01 square units

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Find the area of a parallelogram bounded by the x -axis, the line g ( x ) = 2 , the line f ( x ) = 3 x , and the line parallel to f ( x ) passing through ( 6 , 1 ) .

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For the following exercises, consider this scenario: A town’s population has been decreasing at a constant rate. In 2010 the population was 5,900. By 2012 the population had dropped 4,700. Assume this trend continues.

Predict the population in 2016.

2,300

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Identify the year in which the population will reach 0.

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For the following exercises, consider this scenario: A town’s population has been increased at a constant rate. In 2010 the population was 46,020. By 2012 the population had increased to 52,070. Assume this trend continues.

Predict the population in 2016.

64,170

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Identify the year in which the population will reach 75,000.

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For the following exercises, consider this scenario: A town has an initial population of 75,000. It grows at a constant rate of 2,500 per year for 5 years.

Find the linear function that models the town’s population P as a function of the year, t , where t is the number of years since the model began.

P ( t ) = 75 , 000 + 2500 t

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Find a reasonable domain and range for the function P .

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If the function P is graphed, find and interpret the x - and y -intercepts.

(–30, 0) Thirty years before the start of this model, the town had no citizens. (0, 75,000) Initially, the town had a population of 75,000.

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Questions & Answers

it is the relatively stable flow of income
Chidubem Reply
what is circular flow of income
Divine Reply
branches of macroeconomics
SHEDRACK Reply
what is Flexible exchang rate?
poudel Reply
is gdp a reliable measurement of wealth
Atega Reply
introduction to econometrics
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Tom
Why is unemployment rate never zero at full employment?
Priyanka Reply
bcoz of existence of frictional unemployment in our economy.
Umashankar
what is flexible exchang rate?
poudel
due to existence of the pple with disabilities
Abdulraufu
the demand of a good rises, causing the demand for another good to fall
Rushawn Reply
is it possible to leave every good at the same level
Joseph
I don't think so. because check it, if the demand for chicken increases, people will no longer consume fish like they used to causing a fall in the demand for fish
Anuolu
is not really possible to let the value of a goods to be same at the same time.....
Salome
Suppose the inflation rate is 6%, does it mean that all the goods you purchase will cost 6% more than previous year? Provide with reasoning.
Geetha Reply
Not necessarily. To measure the inflation rate economists normally use an averaged price index of a basket of certain goods. So if you purchase goods included in the basket, you will notice that you pay 6% more, otherwise not necessarily.
Waeth
discus major problems of macroeconomics
Alii Reply
what is the problem of macroeconomics
Yoal
Economic growth Stable prices and low unemployment
Ephraim
explain inflationcause and itis degre
Miresa Reply
what is inflation
Getu
increase in general price levels
WEETO
Good day How do I calculate this question: C= 100+5yd G= 2000 T= 2000 I(planned)=200. Suppose the actual output is 3000. What is the level of planned expenditures at this level of output?
Chisomo Reply
how to calculate actual output?
Chisomo
how to calculate the equilibrium income
Beshir
Criteria for determining money supply
Thapase Reply
who we can define macroeconomics in one line
Muhammad
Aggregate demand
Mohammed
C=k100 +9y and i=k50.calculate the equilibrium level of output
Mercy Reply
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money as unit of account means what?
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A unit of account is something that can be used to value goods and services and make calculations
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Muhammad
I want to know how can we define macroeconomics in one line
Muhammad
it must be .9 or 0.9 no Mpc is greater than 1 Y=100+.9Y+50 Y-.9Y=150 0.1Y/0.1=150/0.1 Y=1500
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hi can someone help me on this question If a negative shocks shifts the IS curve to the left, what type of policy do you suggest so as to stabilize the level of output? discuss your answer using appropriate graph.
Galge Reply
if interest rate is increased this will will reduce the level of income shifting the curve to the left ◀️
Kalombe
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Source:  OpenStax, College algebra. OpenStax CNX. Feb 06, 2015 Download for free at https://legacy.cnx.org/content/col11759/1.3
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