Integral: Solving the Difficult One

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SUMMARY

The integral $$\int \left(\frac{x-1}{x+1}\right)^4\,dx$$ can be solved by substituting $$u=x+1$$, which simplifies the expression to $$\left(1-2u^{-1}\right)^4$$. Applying the binomial theorem results in the expansion $$16u^{-4}-32u^{-3}+24u^{-2}-8u^{-1}+1$$. The integration can then be performed term by term, followed by back-substitution for $$u$$ to obtain the final result.

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Natarajan
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Consider the following:

$$\int \left(\frac{x-1}{x+1}\right)^4\,dx$$

I am unable to solve this.
 
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Hello and welcome to MHB, Natarajan!

I have moved your thread since this forum is a better fit for your question.

I think the first thing I would do is write:

$$\frac{x-1}{x+1}=\frac{x+1-2}{x+1}=1-\frac{2}{x+1}$$

Let's substitute:

$$u=x+1\implies du=dx$$

Now, apply the binomial theorem:

$$\left(1-2u^{-1}\right)^4=16u^{-4}-32u^{-3}+24u^{-2}-8u^{-1}+1$$

Now you can integrate term by term, and then back-substitute for $u$. Can you proceed?
 

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