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Aduceti la forma mai simpla ex: 1+1\5*1\9+...+1\2005*1\2009+1\2009*1\2013=

Răspuns :

[tex]1+ \frac{1}{5*9} +...+ \frac{1}{2009*2013} =\\ =1+ \frac{1}{4} ( \frac{1}{5} -\frac{1}{9})+...+\frac{1}{4} ( \frac{1}{2009} -\frac{1}{2013})=\\ =1+ \frac{1}{4} ( \frac{1}{5} -\frac{1}{9}+...+\frac{1}{2009} -\frac{1}{2013})=\\ =1+ \frac{1}{4} ( \frac{1}{5} -\frac{1}{2013})=\\ =1+\frac{1}{4} * \frac{2008}{10065} = \frac{10567}{10065} [/tex]