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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

how does the planets on our solar system orbit
cheten Reply
how many Messier objects are there in space
satish Reply
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Richard Reply
what are astronomy
Issan Reply
Astronomy (from Ancient Greek ἀστρονομία (astronomía) 'science that studies the laws of the stars') is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution.
Rafael
vjuvu
Elgoog
what is big bang theory?
Rosemary
what type of activity astronomer do?
Rosemary
No
Richard
the big bang theory is a theory which states that all matter was compressed together in one place the matter got so unstable it exploded releasing All its contents in the form of hydrogen
Roaul
I want to be an astronomer. That's my dream
Astrit
Who named the the whole galaxy?
Shola Reply
solar Univers
GPOWER
what is space
Richard
what is the dark matter
Richard
what are the factors upon which the atmosphere is stratified
Nicholas Reply
is the big bang the sun
Folakemi Reply
no
Sokak
bigbang is the beginning of the universe
Sokak
but thats just a theory
Sokak
nothing will happen, don't worry brother.
Vansh
what does comet means
GANGAIN Reply
these are Rocky substances between mars and jupiter
GANGAIN
Comets are cosmic snowballs of frozen gases , rock and dust that orbit the sun. They are mostly found between the orbits of Venus and Mercury.
Aarya
hllo
John
hi
John
qt rrt
John
r u there
John
hey can anyone guide me abt international astronomy olympiad
sahil
how can we learn right and true ?
Govinda Reply
why the moon is always appear in an elliptical shape
Gatjuol Reply
Because when astroid hit the Earth then a piece of elliptical shape of the earth was separated which is now called moon.
Hemen
what's see level?
lidiya Reply
Did you mean eye sight or sea level
Minal
oh sorry it's sea level
lidiya
according to the theory of astronomers why the moon is always appear in an elliptical orbit?
Gatjuol
hi !!! I am new in astronomy.... I have so many questions in mind .... all of scientists of the word they just give opinion only. but they never think true or false ... i respect all of them... I believes whole universe depending on true ...থিউরি
Govinda
hello
Jackson
hi
Elyana
we're all stars and galaxies a part of sun. how can science prove thx with respect old ancient times picture or books..or anything with respect to present time .but we r a part of that universe
w astronomy and cosmology!
Michele
another theory of universe except big ban
Albash Reply
how was universe born
Asmit Reply
there many theory to born universe but what is the reality of big bang theory to born universe
Asmit
what is the exact value of π?
Nagalakshmi
by big bang
universal
there are many theories regarding this it's on you believe any theory that you think is true ex. eternal inflation theory, oscillation model theory, multiple universe theory the big bang theory etc.
Aarya
I think after Big Bang!
Michele
from where on earth could u observe all the stars during the during the course of an year
Karuna Reply
I think it couldn't possible on earth
Nagalakshmi
in this time i don't Know
Michele
is that so. the question was in the end of this chapter
Karuna
in theory, you could see them all from the equator (though over the course of a year, not at pne time). stars are measured in "declination", which is how far N or S of the equator (90* to -90*). Polaris is the North star, and is ALMOST 90* (+89*). So it would just barely creep over the horizon.
Christopher
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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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