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Access the following online resource for additional instruction and practice with properties of limits.

Key concepts

  • The properties of limits can be used to perform operations on the limits of functions rather than the functions themselves. See [link] .
  • The limit of a polynomial function can be found by finding the sum of the limits of the individual terms. See [link] and [link] .
  • The limit of a function that has been raised to a power equals the same power of the limit of the function. Another method is direct substitution. See [link] .
  • The limit of the root of a function equals the corresponding root of the limit of the function.
  • One way to find the limit of a function expressed as a quotient is to write the quotient in factored form and simplify. See [link] .
  • Another method of finding the limit of a complex fraction is to find the LCD. See [link] .
  • A limit containing a function containing a root may be evaluated using a conjugate. See [link] .
  • The limits of some functions expressed as quotients can be found by factoring. See [link] .
  • One way to evaluate the limit of a quotient containing absolute values is by using numeric evidence. Setting it up piecewise can also be useful. See [link] .

Section exercises

Verbal

Give an example of a type of function f whose limit, as x approaches a , is f ( a ) .

If f is a polynomial function, the limit of a polynomial function as x approaches a will always be f ( a ) .

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When direct substitution is used to evaluate the limit of a rational function as x approaches a and the result is f ( a ) = 0 0 , does this mean that the limit of f does not exist?

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What does it mean to say the limit of f ( x ) , as x approaches c , is undefined?

It could mean either (1) the values of the function increase or decrease without bound as x approaches c , or (2) the left and right-hand limits are not equal.

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Algebraic

For the following exercises, evaluate the limits algebraically.

lim x 2 ( 5 x x 2 1 )

10 3

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lim x 2 ( x 2 5 x + 6 x + 2 )

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lim x 3 ( x 2 9 x 3 )

6

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lim x 1 ( x 2 2 x 3 x + 1 )

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lim x 3 2 ( 6 x 2 17 x + 12 2 x 3 )

1 2

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lim x 7 2 ( 8 x 2 + 18 x 35 2 x + 7 )

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lim x 3 ( x 2 9 x 5 x + 6 )

6

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lim x 3 ( 7 x 4 21 x 3 12 x 4 + 108 x 2 )

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lim x 3 ( x 2 + 2 x 3 x 3 )

does not exist

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lim h 0 ( ( 3 + h ) 3 27 h )

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lim h 0 ( ( 2 h ) 3 8 h )

12

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lim h 0 ( ( h + 3 ) 2 9 h )

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lim h 0 ( 5 h 5 h )

5 10

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lim x 0 ( 3 x 3 x )

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lim x 9 ( x 2 81 3 x )

108

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lim x 1 ( x x 2 1 x )

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lim x 0 ( x 1 + 2 x 1 )

1

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lim x 1 2 ( x 2 1 4 2 x 1 )

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lim x 4 ( x 3 64 x 2 16 )

6

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lim x 2 ( | x 2 | x 2 )

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lim x 2 + ( | x 2 | x 2 )

1

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lim x 2 ( | x 2 | x 2 )

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lim x 4 ( | x 4 | 4 x )

1

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lim x 4 + ( | x 4 | 4 x )

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lim x 4 ( | x 4 | 4 x )

does not exist

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lim x 2 ( 8 + 6 x x 2 x 2 )

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For the following exercise, use the given information to evaluate the limits: lim x c f ( x ) = 3 , lim x c g ( x ) = 5

lim x c [ 2 f ( x ) + g ( x ) ]

6 + 5

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lim x c [ 3 f ( x ) + g ( x ) ]

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lim x c f ( x ) g ( x )

3 5

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For the following exercises, evaluate the following limits.

lim x 2 cos ( π x )

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lim x 2 sin ( π x )

0

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lim x 2 sin ( π x )

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f ( x ) = { 2 x 2 + 2 x + 1 , x 0 x 3 ,   x > 0 lim x 0 + f ( x )

3

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f ( x ) = { 2 x 2 + 2 x + 1 , x 0 x 3 ,   x > 0 lim x 0 f ( x )

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f ( x ) = { 2 x 2 + 2 x + 1 , x 0 x 3 ,   x > 0 lim x 0 f ( x )

does not exist; right-hand limit is not the same as the left-hand limit.

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lim x 4 x + 5 3 x 4

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lim x 2 + ( 2 x 〚x〛 )

2

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lim x 2 x + 7 3 x 2 x 2

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lim x 3 + x 2 x 2 9

Limit does not exist; limit approaches infinity.

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For the following exercises, find the average rate of change f ( x + h ) f ( x ) h .

f ( x ) = 2 x 2 1

4 x + 2 h

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f ( x ) = x 2 + 4 x 100

2 x + h + 4

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f ( x ) = cos ( x )

cos ( x + h ) cos ( x ) h

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f ( x ) = 1 x

1 x ( x + h )

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f ( x ) = x

1 x + h + x

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Graphical

Find an equation that could be represented by [link] .

Graph of increasing function with a removable discontinuity at (2, 3).
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Find an equation that could be represented by [link] .

Graph of increasing function with a removable discontinuity at (-3, -1).

f ( x ) = x 2 + 5 x + 6 x + 3

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For the following exercises, refer to [link] .

Graph of increasing function from zero to positive infinity.

What is the right-hand limit of the function as x approaches 0?

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What is the left-hand limit of the function as x approaches 0?

does not exist

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Real-world applications

The position function s ( t ) = 16 t 2 + 144 t gives the position of a projectile as a function of time. Find the average velocity (average rate of change) on the interval [ 1 , 2 ] .

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The height of a projectile is given by s ( t ) = 64 t 2 + 192 t Find the average rate of change of the height from t = 1 second to t = 1.5 seconds.

52

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The amount of money in an account after t years compounded continuously at 4.25% interest is given by the formula A = A 0 e 0.0425 t , where A 0 is the initial amount invested. Find the average rate of change of the balance of the account from t = 1 year to t = 2 years if the initial amount invested is $1,000.00.

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Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Practice Key Terms 1

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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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