<< Chapter < Page Chapter >> Page >

Key concepts

  • Integrals of functions over infinite intervals are defined in terms of limits.
  • Integrals of functions over an interval for which the function has a discontinuity at an endpoint may be defined in terms of limits.
  • The convergence or divergence of an improper integral may be determined by comparing it with the value of an improper integral for which the convergence or divergence is known.

Key equations

  • Improper integrals
    a + f ( x ) d x = lim t + a t f ( x ) d x b f ( x ) d x = lim t t b f ( x ) d x + f ( x ) d x = 0 f ( x ) d x + 0 + f ( x ) d x

Evaluate the following integrals. If the integral is not convergent, answer “divergent.”

2 4 d x ( x 3 ) 2

divergent

Got questions? Get instant answers now!

0 2 1 4 x 2 d x

π 2

Got questions? Get instant answers now!

1 x e x d x

2 e

Got questions? Get instant answers now!

x x 2 + 1 d x

Got questions? Get instant answers now!

Without integrating, determine whether the integral 1 1 x 3 + 1 d x converges or diverges by comparing the function f ( x ) = 1 x 3 + 1 with g ( x ) = 1 x 3 .

Converges

Got questions? Get instant answers now!

Without integrating, determine whether the integral 1 1 x + 1 d x converges or diverges.

Got questions? Get instant answers now!

Determine whether the improper integrals converge or diverge. If possible, determine the value of the integrals that converge.

0 e x cos x d x

Converges to 1/2.

Got questions? Get instant answers now!

1 x 2 + 1 d x

π

Got questions? Get instant answers now!

−2 2 d x ( 1 + x ) 2

diverges

Got questions? Get instant answers now!

0 sin x d x

diverges

Got questions? Get instant answers now!

e x 1 + e 2 x d x

Got questions? Get instant answers now!

−1 2 d x x 3

diverges

Got questions? Get instant answers now!

0 3 1 x 1 d x

diverges

Got questions? Get instant answers now!

3 5 5 ( x 4 ) 2 d x

diverges

Got questions? Get instant answers now!

Determine the convergence of each of the following integrals by comparison with the given integral. If the integral converges, find the number to which it converges.

1 d x x 2 + 4 x ; compare with 1 d x x 2 .

Got questions? Get instant answers now!

1 d x x + 1 ; compare with 1 d x 2 x .

Both integrals diverge.

Got questions? Get instant answers now!

Evaluate the integrals. If the integral diverges, answer “diverges.”

0 1 d x x π

diverges

Got questions? Get instant answers now!

0 1 d x 1 x

diverges

Got questions? Get instant answers now!

0 d x x 2 + 1

Got questions? Get instant answers now!

−1 1 d x 1 x 2

π

Got questions? Get instant answers now!

0 e ln ( x ) d x

0.0

Got questions? Get instant answers now!

x ( x 2 + 1 ) 2 d x

0.0

Got questions? Get instant answers now!

Evaluate the improper integrals. Each of these integrals has an infinite discontinuity either at an endpoint or at an interior point of the interval.

0 3 d x 9 x 2

π 2

Got questions? Get instant answers now!

6 24 d t t t 2 36

Got questions? Get instant answers now!

0 4 x ln ( 4 x ) d x

8 ln ( 16 ) 4

Got questions? Get instant answers now!

Evaluate .5 t d x 1 x 2 . (Be careful!) (Express your answer using three decimal places.)

1.047

Got questions? Get instant answers now!

Evaluate 1 4 d x x 2 1 . (Express the answer in exact form.)

Got questions? Get instant answers now!

Evaluate 2 d x ( x 2 1 ) 3 / 2 .

−1 + 2 3

Got questions? Get instant answers now!

Find the area of the region in the first quadrant between the curve y = e −6 x and the x -axis.

Got questions? Get instant answers now!

Find the area of the region bounded by the curve y = 7 x 2 , the x -axis, and on the left by x = 1 .

7.0

Got questions? Get instant answers now!

Find the area under the curve y = 1 ( x + 1 ) 3 / 2 , bounded on the left by x = 3 .

Got questions? Get instant answers now!

Find the area under y = 5 1 + x 2 in the first quadrant.

5 π 2

Got questions? Get instant answers now!

Find the volume of the solid generated by revolving about the x -axis the region under the curve y = 3 x from x = 1 to x = .

Got questions? Get instant answers now!

Find the volume of the solid generated by revolving about the y -axis the region under the curve y = 6 e −2 x in the first quadrant.

3 π

Got questions? Get instant answers now!

Find the volume of the solid generated by revolving about the x -axis the area under the curve y = 3 e x in the first quadrant.

Got questions? Get instant answers now!

The Laplace transform of a continuous function over the interval [ 0 , ) is defined by F ( s ) = 0 e s x f ( x ) d x (see the Student Project). This definition is used to solve some important initial-value problems in differential equations, as discussed later. The domain of F is the set of all real numbers s such that the improper integral converges. Find the Laplace transform F of each of the following functions and give the domain of F .

f ( x ) = cos ( 2 x )

s s 2 + 4 , s > 0

Got questions? Get instant answers now!

Use the formula for arc length to show that the circumference of the circle x 2 + y 2 = 1 is 2 π .

Answers will vary.

Got questions? Get instant answers now!

A function is a probability density function if it satisfies the following definition: f ( t ) d t = 1 . The probability that a random variable x lies between a and b is given by P ( a x b ) = a b f ( t ) d t .

Show that f ( x ) = { 0 if x < 0 7 e −7 x if x 0 is a probability density function.

Got questions? Get instant answers now!

Find the probability that x is between 0 and 0.3. (Use the function defined in the preceding problem.) Use four-place decimal accuracy.

0.8775

Got questions? Get instant answers now!

Chapter review exercises

For the following exercises, determine whether the statement is true or false. Justify your answer with a proof or a counterexample.

e x sin ( x ) d x cannot be integrated by parts.

Got questions? Get instant answers now!

1 x 4 + 1 d x cannot be integrated using partial fractions.

False

Got questions? Get instant answers now!

In numerical integration, increasing the number of points decreases the error.

Got questions? Get instant answers now!

Integration by parts can always yield the integral.

False

Got questions? Get instant answers now!

For the following exercises, evaluate the integral using the specified method.

x 2 sin ( 4 x ) d x using integration by parts

Got questions? Get instant answers now!

1 x 2 x 2 + 16 d x using trigonometric substitution

x 2 + 16 16 x + C

Got questions? Get instant answers now!

x ln ( x ) d x using integration by parts

Got questions? Get instant answers now!

3 x x 3 + 2 x 2 5 x 6 d x using partial fractions

1 10 ( 4 ln ( 2 x ) + 5 ln ( x + 1 ) 9 ln ( x + 3 ) ) + C

Got questions? Get instant answers now!

x 5 ( 4 x 2 + 4 ) 5 / 2 d x using trigonometric substitution

Got questions? Get instant answers now!

4 sin 2 ( x ) sin 2 ( x ) cos ( x ) d x using a table of integrals or a CAS

4 sin 2 ( x ) sin ( x ) x 2 + C

Got questions? Get instant answers now!

For the following exercises, integrate using whatever method you choose.

sin 2 ( x ) cos 2 ( x ) d x

Got questions? Get instant answers now!

x 3 x 2 + 2 d x

1 15 ( x 2 + 2 ) 3 / 2 ( 3 x 2 4 ) + C

Got questions? Get instant answers now!

3 x 2 + 1 x 4 2 x 3 x 2 + 2 x d x

Got questions? Get instant answers now!

1 x 4 + 4 d x

1 16 ln ( x 2 + 2 x + 2 x 2 2 x + 2 ) 1 8 tan −1 ( 1 x ) + 1 8 tan −1 ( x + 1 ) + C

Got questions? Get instant answers now!

For the following exercises, approximate the integrals using the midpoint rule, trapezoidal rule, and Simpson’s rule using four subintervals, rounding to three decimals.

[T] 1 2 x 5 + 2 d x

M 4 = 3.312 , T 4 = 3.354 , S 4 = 3.326

Got questions? Get instant answers now!

[T] 0 π e sin ( x 2 ) d x

Got questions? Get instant answers now!

[T] 1 4 ln ( 1 / x ) x d x

M 4 = −0.982 , T 4 = −0.917 , S 4 = −0.952

Got questions? Get instant answers now!

For the following exercises, evaluate the integrals, if possible.

1 1 x n d x , for what values of n does this integral converge or diverge?

Got questions? Get instant answers now!

1 e x x d x

approximately 0.2194

Got questions? Get instant answers now!

For the following exercises, consider the gamma function given by Γ ( a ) = 0 e y y a 1 d y .

Show that Γ ( a ) = ( a 1 ) Γ ( a 1 ) .

Got questions? Get instant answers now!

Extend to show that Γ ( a ) = ( a 1 ) ! , assuming a is a positive integer.

The fastest car in the world, the Bugati Veyron, can reach a top speed of 408 km/h. The graph represents its velocity.

This figure has a graph in the first quadrant. It increases to where x is approximately 03:00 mm:ss and then drops off steep. The maximum height of the graph, here the drop occurs is approximately 420 km/h.
Got questions? Get instant answers now!

[T] Use the graph to estimate the velocity every 20 sec and fit to a graph of the form v ( t ) = a exp b x sin ( c x ) + d . ( Hint: Consider the time units.)

Got questions? Get instant answers now!

[T] Using your function from the previous problem, find exactly how far the Bugati Veyron traveled in the 1 min 40 sec included in the graph.

Answers may vary. Ex: 9.405 km

Got questions? Get instant answers now!

Questions & Answers

how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
what is inflammation
Shelly Reply
part of a tissue or an organ being wounded or bruised.
Wilfred
what term is used to name and classify microorganisms?
Micheal Reply
Binomial nomenclature
adeolu
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply
Practice Key Terms 1

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Calculus volume 2. OpenStax CNX. Feb 05, 2016 Download for free at http://cnx.org/content/col11965/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Calculus volume 2' conversation and receive update notifications?

Ask