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[[tex] \frac{1}{ \sqrt{1}+ \sqrt{2} } [/tex] + ...... +[tex] \frac{1}{ \sqrt{98 + \sqrt{99} } } [/tex] = ?
Va roog , ajutoor !!


Răspuns :

Rationalizam fiecare raport si obtinem:
[tex] \sqrt{2} - \sqrt{1} + \sqrt{3} - \sqrt{2} +...+ \sqrt{99}- \sqrt{98} =\sqrt{99}-1=3 \sqrt{11} -1[/tex]