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Real-world applications

For the following exercises, explain the notation in words. The volume f ( t ) of a tank of gasoline, in gallons, t minutes after noon.

f ' ( 30 ) = −20

At 12:30 p.m. , the rate of change of the number of gallons in the tank is –20 gallons per minute. That is, the tank is losing 20 gallons per minute.

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f ' ( 200 ) = 30

At 200 minutes after noon, the volume of gallons in the tank is changing at the rate of 30 gallons per minute.

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For the following exercises, explain the functions in words. The height, s , of a projectile after t seconds is given by s ( t ) = 16 t 2 + 80 t .

s ( 2 ) = 96

The height of the projectile after 2 seconds is 96 feet.

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s ( 3 ) = 96

The height of the projectile at t = 3 seconds is 96 feet.

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s ( 0 ) = 0 , s ( 5 ) = 0.

The height of the projectile is zero at t = 0 and again at t = 5. In other words, the projectile starts on the ground and falls to earth again after 5 seconds.

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For the following exercises, the volume V of a sphere with respect to its radius r is given by V = 4 3 π r 3 .

Find the average rate of change of V as r changes from 1 cm to 2 cm.

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Find the instantaneous rate of change of V when r = 3  cm .

36 π

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For the following exercises, the revenue generated by selling x items is given by R ( x ) = 2 x 2 + 10 x .

Find the average change of the revenue function as x changes from x = 10 to x = 20.

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Find R ' ( 10 ) and interpret.

$50.00 per unit, which is the instantaneous rate of change of revenue when exactly 10 units are sold.

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Find R ' ( 15 ) and interpret. Compare R ' ( 15 ) to R ' ( 10 ) , and explain the difference.

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For the following exercises, the cost of producing x cellphones is described by the function C ( x ) = x 2 4 x + 1000.

Find the average rate of change in the total cost as x changes from x = 10  to  x = 15.

$21 per unit

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Find the approximate marginal cost, when 15 cellphones have been produced, of producing the 16 th cellphone.

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Find the approximate marginal cost, when 20 cellphones have been produced, of producing the 21 st cellphone.

$36

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Extension

For the following exercises, use the definition for the derivative at a point x = a , lim x a f ( x ) f ( a ) x a , to find the derivative of the functions.

f ( x ) = 5 x 2 x + 4

f ' ( x ) = 10 a 1

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f ( x ) = x 2 + 4 x + 7

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f ( x ) = 4 3 x 2

4 ( 3 x ) 2

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Chapter review exercises

Finding Limits: A Numerical and Graphical Approach

For the following exercises, use [link] .

Graph of a piecewise function with two segments. The first segment goes from (-1, 2), a closed point, to (3, -6), a closed point, and the second segment goes from (3, 5), an open point, to (7, 9), a closed point.

lim x −1 + f ( x )

2

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lim x −1 f ( x )

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lim x 1 f ( x )

does not exist

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At what values of x is the function discontinuous? What condition of continuity is violated?

Discontinuous at  x = 1 ( lim x a f ( x )  does not exist ) , x = 3   ( jump discontinuity ) , and  x = 7   ( lim x a f ( x )  does not exist ) .

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Using [link] , estimate lim x 0 f ( x ) .

x F ( x )
−0.1 2.875
−0.01 2.92
−0.001 2.998
0 Undefined
0.001 2.9987
0.01 2.865
0.1 2.78145
0.15 2.678

3

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For the following exercises, with the use of a graphing utility, use numerical or graphical evidence to determine the left- and right-hand limits of the function given as x approaches a .   If the function has limit as x approaches a , state it. If not, discuss why there is no limit.

f ( x ) = { | x | 1 , i f x 1 x 3 , i f x = 1    a = 1

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f ( x ) = { 1 x + 1 , i f x = 2 ( x + 1 ) 2 , i f x 2    a = 2

lim x 2 f ( x ) = 1

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f ( x ) = { x + 3 , i f x < 1 x 3 , i f x > 1    a = 1

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Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
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John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
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hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Precalculus. OpenStax CNX. Jan 19, 2016 Download for free at https://legacy.cnx.org/content/col11667/1.6
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