I am given this expansion:(adsbygoogle = window.adsbygoogle || []).push({});

x + 2^2 x^2 + 3^2 x^3 + 4^2 x^4 + ... + k^2 x^k + ...

To get the function that yields this expansion, I cannot figure out the manipulation to (x)/(1-x)

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# Given a particular expansion, find the function in powers of x

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