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How does my book get from this step to this step?

  • Thread starter frasifrasi
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  • #1
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[SOLVED] How does my book get from this step to this step?

My book went from int of dx/ ( sqrt(x)*(x+1) )

to

2arctan sqrt (x) -- WTH?

I thought the form for arctan was dx/a^2 + u^2 and I don't see that in the given integrand?

Can anyone help?
 

Answers and Replies

  • #2
arildno
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Substitute [tex]u=\sqrt{x}[/tex], and see what you get.
 
  • #3
Astronuc
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If x=u2, then dx = 2 u du

sqrt (x) = u, and

x+1 = u2 + 1
 
  • #4
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astronuc, did you arrive at that by using the substitution arildno suggested?
 
  • #5
HallsofIvy
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Well, arildno said "u= [itex]\sqrt{x}[/itex]" and Astronuc said "x= u2". Look the same to me!
 
  • #6
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Ha, you rascal!
 

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