Let [tex]u_n[/tex] be a sequence of positive real number.(adsbygoogle = window.adsbygoogle || []).push({});

If [tex]\sum_{n=1}^{\infty}u_n^{2}[/tex] finite + (condition??) then [tex]\sum_{n=1}^{\infty}u_n[/tex] finite.

I want to find the condition.Please help me.

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# Sum math problem

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