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We now present a list of integrals for you to examine. You should look at them
all and try to decide how to attack each. Once you have an idea how to do them,
you should do a few of each kind. You will not do integrals fluently until you
have done a dozen or so, and have fallen into all the standard traps, and then
you will know what to avoid. Here are some hints which probably will not help
until you make these mistakes yourself.
The most common mistake is forgetting a small factor when changing variables and
relating dx with some du.
Losing a small factor when copying one line to the next is also very common as
is dropping a sign.
Forgetting that you are integrating and writing a derivative instead of an integral
of some common function which you integrate by inspection where the integral is
called for, is fairly common.
Failing to adjust the limits of integration upon changing variables is another
common error.
Failing to pay attention to the singularities of the integrand, and not noticing
that you have integrated over one, is rarer but only because you rarely run into
the problem.
Exercises: Describe what you would do to evaluate each of the following
integrals. Then do five of them.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
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