29.03.2012 - teoria numerelor [cls IX-XI]
Scris: Sâm Mar 31, 2012 6:58 pm
Fie $a_1,a_2,...,a_k,n\in \Bbb{N}$ cu $1<a_1<a_2<...<a_k<n$ si $[a_i;a_j]>n\ (\forall)\ i,j\le k,\ i\neq j$. Sa se arate ca $\dfrac{1}{a_1}+\dfrac{1}{a_2}+...+\dfrac{1}{a_k}<2$.
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