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2/3x5 + 2/5x7 + 2/7x9 +. + 2/85x87.

Răspuns :

Răspuns:

[tex] \frac{2}{3} \times 5 + \frac{2}{5} \times 7 + \frac{2}{7} \times 9 + \frac{2}{85} \times 87 = \frac{10}{3} + \frac{14}{5} + \frac{18}{7} + \frac{174}{85} = \frac{19192}{1785} [/tex]