Please help - integration

  • Thread starter mathrocks
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  • #1
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This one integral has been given me some problems.

integral of dx/(x-sqrt(x+2))

please keep in mind im only in calc 2.
 

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  • #2
Tom Mattson
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mathrocks said:
This one integral has been given me some problems.

integral of dx/(x-sqrt(x+2))

please keep in mind im only in calc 2.

You can do a u-substitution with u=(x+2)1/2. Then du=(1/2)(x+2)-1/2.

Now, you'll find that you don't have the du/dx in your integral, so you'll have to supply it yourself by multiplying the numerator and denominator of the integrand by 2(x+2)1/2 and separating factors accordingly.

That will turn your integrand into a rational function of u which will be much easier to integrate.
 
  • #3
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Well first thing i always do is when i have any function given like this is to rationalize it ..meaning multiply all of this with (x+sqrt(x+2))/(x+sqrt(x+2))
You will get then this sqrt up...
(x+sqrt(x+2)) / ((x^2)-x-2)
then you have (x+sqrt(x+2)) / (x-2)(x+1)
Then you can simply seperate this integral into two.. int_x / ((x-2)(x+1))dx + int_sqrt(x+2) / ((x-2)(x+1))dx
from there by substitution you can easily sole both of them
:wink:
 

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