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Consider the sequence of functions $ f_n : [0,1] \to \mathbb{R} $ given by

$$ f_n(x) = (n+1)(n+2)(1-x)x^n. $$

Calculate:

$$ \int \lim_{n \to \infty} f_n(x) \, d\mu_L. $$

It is evident to me, that this sequences becomes zero. However i am not being able to show this statement cleanly. I have tried rewriting the function as $$f_n(x)= (\partial^2/\partial x^2 x^{n+2}) \cdot(1-x) $$ And in this form, it is evident, that the limit over n only effects the first part, however ,i have no mechanism to switch the limit with the partial derivative.

And in a differnt note, can one find a lesbegue integrable function $g$ such that $$\vert f_n(x)\vert \leq g$$ in order to apply the theorem of Lesbegue? The Integral of the function itself is not hard to calculate, and then apply the limit to the result.

Madder
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    For $0\le x<1$ we have $f_n(x)^{1/n}\to x<1.$ Hence by the root test we get $f_n(x)\to 0.$ Besides $f_n(1)=0.$ Thus $ f_n(x)\to 0$ for $0\le x\le 1.$ – Ryszard Szwarc Sep 21 '24 at 20:56

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