How to calculate $\int_{-1}^{1} \left( \frac{1}{2^nn!}\frac{d^n}{dx^n}\left(x^2-1\right)^n \left(x\right)\right)^2dx$?

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I'm trying to calculate $$\int_{-1}^{1} \left( \frac{1}{2^nn!}\frac{d^n}{dx^n}\left(x^2-1\right)^n \left(x\right)\right)^2dx$$ I found that this question is about to Legendre polynomials and Rodrigues' formula. However, I still couldn't get an answer for this question. How to make this computation in a good way?

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Actually if you search for the properties of Legendre's Polynomials you will get the answer to your question eventhough looks complicated at first sight!

A good reference is - here,check the properties there.

$\int_{-1}^{1} (P_{n})^2 dx = \frac{2}{2n + 1}$ where $P_{n}(x)$ is the Legendre Polynomial $\frac{1}{2^nn!}\frac{d^n}{dx^n}\left(x^2-1\right)^n \left(x\right)$

Hope this illustrates!