Integration, where have i gone wrong?

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The discussion centers on the integration of the function \(\int \arctan(\sqrt{x}) \, dx\) using integration by parts. The user correctly identifies \(dv = dx\) and \(v = x\), but encounters an error in the calculation of \(du\) and the subsequent integral. The mistake arises in the manipulation of the integral \(\int \frac{x}{1+x} \, dx\), leading to an incorrect final expression. The correct approach involves recognizing the substitution \(y = \sqrt{x}\) and transforming the integral into a more manageable form.

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Students and professionals in mathematics, particularly those studying calculus and integral techniques, as well as educators looking for examples of common integration errors.

Dell
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[tex]\int[/tex]arctg[tex]\sqrt{x}[/tex]dx

using[tex]\int[/tex]udv=uv-[tex]\int[/tex]vdu

dv=dx
v=x

u=arctg[tex]\sqrt{x}[/tex]
du=u'dx=[1/(1+x)]dx

[tex]\int[/tex]arctg[tex]\sqrt{x}[/tex]dx=xarctg[tex]\sqrt{x}[/tex] - [tex]\int[/tex]x*[1/(1+x)]dx
=xarctg[tex]\sqrt{x}[/tex] - [tex]\int[/tex][x/(1+x)]dx
=xarctg[tex]\sqrt{x}[/tex] - [tex]\int[/tex]1-[1/(1+x)]dx
=xarctg[tex]\sqrt{x}[/tex] - x+ln|x+1|+c
but this is wrong, where have i made the mistake?
 
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The derivative of arctan(sqrt(x)) is (1/(1+x))*1/2(sqrt(x)), you can still solve this question by looking at:
sqrt(x)/(1+x)dx=2/3(d(x^3/2))/(1+(x^3/2)^(2/3))
sqrt(x)dx=2/3d(x^3/2)
and the integral of dy/(1+y^2/3)
can be solved by writing y^1/3=sinh(t).

I am not sure this will work, but I think that there is no easy way here.
 
thanks
 

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