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Section exercises

Verbal

Terry is skiing down a steep hill. Terry's elevation, E ( t ) , in feet after t seconds is given by E ( t ) = 3000 70 t . Write a complete sentence describing Terry’s starting elevation and how it is changing over time.

Terry starts at an elevation of 3000 feet and descends 70 feet per second.

Maria is climbing a mountain. Maria's elevation, E ( t ) , in feet after t minutes is given by E ( t ) = 1200 + 40 t . Write a complete sentence describing Maria’s starting elevation and how it is changing over time.

Jessica is walking home from a friend’s house. After 2 minutes she is 1.4 miles from home. Twelve minutes after leaving, she is 0.9 miles from home. What is her rate in miles per hour?

3 miles per hour

Sonya is currently 10 miles from home and is walking farther away at 2 miles per hour. Write an equation for her distance from home t hours from now.

A boat is 100 miles away from the marina, sailing directly toward it at 10 miles per hour. Write an equation for the distance of the boat from the marina after t hours.

d ( t ) = 100 10 t

Timmy goes to the fair with $40. Each ride costs $2. How much money will he have left after riding n rides?

Algebraic

For the following exercises, determine whether the equation of the curve can be written as a linear function.

y = 1 4 x + 6

Yes.

y = 3 x 5

y = 3 x 2 2

No.

3 x + 5 y = 15

3 x 2 + 5 y = 15

No.

3 x + 5 y 2 = 15

2 x 2 + 3 y 2 = 6

No.

x 3 5 = 2 y

For the following exercises, determine whether each function is increasing or decreasing.

f ( x ) = 4 x + 3

Increasing.

g ( x ) = 5 x + 6

a ( x ) = 5 2 x

Decreasing.

b ( x ) = 8 3 x

h ( x ) = 2 x + 4

Decreasing.

k ( x ) = 4 x + 1

j ( x ) = 1 2 x 3

Increasing.

p ( x ) = 1 4 x 5

n ( x ) = 1 3 x 2

Decreasing.

m ( x ) = 3 8 x + 3

For the following exercises, find the slope of the line that passes through the two given points.

( 2 ,   4 ) and ( 4 ,  10 )

3

( 1 ,  5 ) and ( 4 ,  11 )

( −1 , 4 ) and ( 5 , 2 )

1 3

( 8 , −2 ) and ( 4 , 6 )

( 6 ,   11 ) and ( 4 ,   3 )

4 5

For the following exercises, given each set of information, find a linear equation satisfying the conditions, if possible.

f ( 5 ) = 4 , and f ( 5 ) = 2

f ( −1 ) = 4 and f ( 5 ) = 1

f ( x ) = 1 2 x + 7 2

( 2 , 4 ) and ( 4 , 10 )

Passes through ( 1 , 5 ) and ( 4 , 11 )

y = 2 x + 3

Passes through ( 1 ,  4 ) and ( 5 ,  2 )

Passes through ( 2 ,  8 ) and ( 4 ,  6 )

y = 1 3 x + 22 3

x intercept at ( 2 ,  0 ) and y intercept at ( 0 , −3 )

x intercept at ( 5 ,  0 ) and y intercept at ( 0 ,  4 )

y = 4 5 x + 4

Graphical

For the following exercises, find the slope of the lines graphed.

5 4

For the following exercises, write an equation for the lines graphed.

y = 2 3 x + 1

y = 2 x + 3

y = 3

Numeric

For the following exercises, which of the tables could represent a linear function? For each that could be linear, find a linear equation that models the data.

x 0 5 10 15
g ( x ) 5 –10 –25 –40

Linear, g ( x ) = 3 x + 5

x 0 5 10 15
h ( x ) 5 30 105 230
x 0 5 10 15
f ( x ) –5 20 45 70

Linear, f ( x ) = 5 x 5

x 5 10 20 25
k ( x ) 28 13 58 73
x 0 2 4 6
g ( x ) 6 –19 –44 –69

Linear, g ( x ) = 25 2 x + 6

x 2 4 6 8
f ( x ) –4 16 36 56
x 2 4 6 8
f ( x ) –4 16 36 56

Linear, f ( x ) = 10 x 24

x 0 2 6 8
k ( x ) 6 31 106 231

Technology

If f is a linear function, f ( 0.1 ) = 11.5 ,    and   f ( 0.4 ) = 5.9 , find an equation for the function.

f ( x ) = 58 x + 17.3

Graph the function f on a domain of [ 10 ,   10 ] :   f ( x ) = 0.02 x 0.01. Enter the function in a graphing utility. For the viewing window, set the minimum value of x to be 10 and the maximum value of x to be 10.

Graph the function f on a domain of [ 10 ,   10 ] : f x ) = 2 , 500 x + 4 , 000

Practice Key Terms 7

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Source:  OpenStax, Essential precalculus, part 1. OpenStax CNX. Aug 26, 2015 Download for free at http://legacy.cnx.org/content/col11871/1.1
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