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Intergration (basic)

  • Thread starter geffman1
  • Start date
  • #1
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Homework Statement



hey guys i was wondering if anyone could show my how to intergrate sqrt(x2+9). any help would be greatfully appreciated. the sqaure root is over everything:rolleyes:

P.s i have looked at table of intergral but cant see one that looks similar.


Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
gabbagabbahey
Homework Helper
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Use integration by parts with [itex]u=\sqrt{x^2+9}[/itex] and [itex]dv=dx[/itex]...
 
  • #3
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thanks but i have never used any of those methods before?
 
  • #4
Cyosis
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You haven't been taught integration by parts yet? Do you know substitutions, if so try [itex]x=3 \sinh u[/itex]. If both these methods are alien to you they probably expect you to compare it to a standard integral somewhere listed in the back or front of your calculus book.
 
  • #5
HallsofIvy
Science Advisor
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Yet another way is to let [itex]x= 3tan(\theta)[/itex]. Then [itex]dx= 3sec^2(\theta)[/itex] and [itex]\sqrt{x^2+ 9}= \sqrt{9tan^2(\theta)+ 9}= 3\sqrt{tan^2(\theta)+ 1}= 3sec(\theta)[/itex].
 

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