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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

Ayele, K., 2003. Introductory Economics, 3rd ed., Addis Ababa.
Widad Reply
can you send the book attached ?
Ariel
?
Ariel
What is economics
Widad Reply
the study of how humans make choices under conditions of scarcity
AI-Robot
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn Reply
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn
what is ecnomics
Jan Reply
this is the study of how the society manages it's scarce resources
Belonwu
what is macroeconomic
John Reply
macroeconomic is the branch of economics which studies actions, scale, activities and behaviour of the aggregate economy as a whole.
husaini
etc
husaini
difference between firm and industry
husaini Reply
what's the difference between a firm and an industry
Abdul
firm is the unit which transform inputs to output where as industry contain combination of firms with similar production 😅😅
Abdulraufu
Suppose the demand function that a firm faces shifted from Qd  120 3P to Qd  90  3P and the supply function has shifted from QS  20  2P to QS 10  2P . a) Find the effect of this change on price and quantity. b) Which of the changes in demand and supply is higher?
Toofiq Reply
explain standard reason why economic is a science
innocent Reply
factors influencing supply
Petrus Reply
what is economic.
Milan Reply
scares means__________________ends resources. unlimited
Jan
economics is a science that studies human behaviour as a relationship b/w ends and scares means which have alternative uses
Jan
calculate the profit maximizing for demand and supply
Zarshad Reply
Why qualify 28 supplies
Milan
what are explicit costs
Nomsa Reply
out-of-pocket costs for a firm, for example, payments for wages and salaries, rent, or materials
AI-Robot
concepts of supply in microeconomics
David Reply
economic overview notes
Amahle Reply
identify a demand and a supply curve
Salome Reply
i don't know
Parul
there's a difference
Aryan
Demand curve shows that how supply and others conditions affect on demand of a particular thing and what percent demand increase whith increase of supply of goods
Israr
Hi Sir please how do u calculate Cross elastic demand and income elastic demand?
Abari
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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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