Integral involving square root -

winbacker
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Homework Statement



integrate sqrt(1-x^-2/3)^1/2.

Homework Equations





The Attempt at a Solution



The only thing I can think of is u substitution with u = 1 - x^-2/3. Obviously this cannot work because du differs by more than just a constant.

I guess I need to somehow factor this equation but I do not know how. I think I can pull out an x^1/3 or something but I'm not sure. Any help would be appreciated.
 
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Whenever you see stuff like that in the square root, always think "Trig Substitution"!

Hint: 1-sin(x)^2 = cos(x)^2.
 
Do you mean

<br /> \sqrt{1-x^{-2/3}}<br />

or do you mean (as you've written)
<br /> \sqrt{(1-x^{-2/3})^{1/2}}<br />
 
the first one
 
maze said:
Whenever you see stuff like that in the square root, always think "Trig Substitution"!

Hint: 1-sin(x)^2 = cos(x)^2.

I'm not sure that trig substitution is the way to go in this problem. Trig substitution is a viable alternative for integrals that involve
\sqrt{a^2 + x^2}
\sqrt{a^2 - x^2}
\sqrt{x^2 - a^2}

Maybe it can be made to work in the OP's problem, but I don't see it.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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