[tex]\bf \cfrac{1}{2},\cfrac{2}{3},\cfrac{3}{4},\cfrac{4}{5},\cfrac{5}{6}\qquad \sum\limits_{k=1}^5\ \cfrac{k}{k+1}
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-11,12,-13,14,-15,16\qquad \sum\limits_{k=1}^6\ (-1)^k(k+10)\\\\
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\begin{array}{lllllllllll}
9&,&-16&,&25&,&-36&,&49&,&-64\\\\
(3)^2&,&-(4)^2&,&(5)^2&,&-(6)^2&,&(7)^2&,&-(8)^2
\end{array}
\\\\\\
\sum\limits_{k=1}^6\ (-1)^{k+1}(k+2)^2[/tex]
[tex]\bf -------------------------------\\\\
\begin{array}{lllllllllll}
3&,&\frac{3}{2}&,&1&,&\frac{3}{4}&,&\frac{3}{5}\\\\
\frac{3}{1}&,&\frac{3}{2}&,&\frac{3}{3}&,&\frac{3}{4}&,&\frac{3}{5}
\end{array}\qquad \sum\limits_{k=1}^5\ \cfrac{3}{k}[/tex]
