integration tutorial: analysis
Consider the integral
0ln(2) [
e2x / sqrt(
e2x) ]
dx
This is a definite integral,
so we need to find
the area under the integrand f(x),
which we do by using the Fundamental Theorem of Calculus: we find an
antiderivative, evaluate it at the endpoints of the integral, and
take the difference of the values.
To find an antiderivative of
f(
x), we go through
our list of integration methods:
- Recognize elementary antiderivatives
- Rewrite the integrand to make it easier
- Use substitution to reverse the chain rule or simplify the
integrand
- Use integration by parts
- Use inspection to see the value of a definite
integral
to find one that works for this integrand. In this case,
only one method is appropriate. We can rewrite the integrand: use properties of exponents to combine the numerator and
denominator of the fraction to give an expression that is more easily integrable.
This is shown below.
Rewriting:
Use properties of exponents to combine the numerator and
denominator of the fraction to rewrite the integral:
[ e2x / sqrt(e2x) ]
=
ex.
Thus,

[
e2x / sqrt(
e2x) ]
dx
=
exdx
which can be evaluated using
basic antidifferentiation, to obtain
exdx
=
(
ex) +
C.
To evaluate the definite integral, we take this antiderivative,
evaluate it at the endpoints of the integral (0 and ln(2)),
and take the difference of the values. This gives
[ (e(ln(2))) ] - [ (e(0)) ] = 1.
integration analysis
Last Modified: Wed Feb 6 13:53:59 EST 2002
Comments to
glarose@umich.edu
©2002 Gavin LaRose, UM Math Dept.