I just don't understand why it goes like this...why 'therefore'?(adsbygoogle = window.adsbygoogle || []).push({});

i know (x^2)f''(x)+xf'(x)+((x^2)-1)f(x)) = x(xf''(x)+f'(x)+xf(x)) - f(x), but why it goes to zero when taking (d^n/dx^n)?

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# Homework Help: Just couldnt figure this out = (2)

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