[Risolto] Es. N. 677

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677)

$\frac{[-(-1)^2-\big(-\frac{1}{3}\big)^2\big]·\big(\frac{1}{2}-\frac{3}{4}-\frac{1}{5}\big)}{\big[\big(\frac{4}{21}-\frac{2}{3}\big)·\big(-\frac{1}{10}-\frac{1}{5}\big)-\big(\frac{4}{7}+1\big)\big] : \big(\frac{6}{7}+2\big)}$ =

= $\frac{[-1-\frac{1}{9}\big]·\big(\frac{10-15-4}{20}\big)}{\big[\big(\frac{4-14}{21}\big)·\big(\frac{-1-2}{10}\big)-\big(\frac{4+7}{7}\big)\big] : \big(\frac{6+14}{7}\big)}$ =

= $\frac{[\frac{-9-1}{9}\big]·\big(-\frac{9}{20}\big)}{\big[\big(-\frac{10}{21}\big)·\big(-\frac{3}{10}\big)-\frac{11}{7}\big] : \frac{20}{7}}$ =

= $\frac{-\frac{10}{9}·\big(-\frac{9}{20}\big)}{\big[\big(-\frac{1}{7}\big)·\big(-\frac{1}{1}\big)-\frac{11}{7}\big] · \frac{7}{20}}$ =

= $\frac{-\frac{1}{1}·\big(-\frac{1}{2}\big)}{\big[\frac{1}{7}-\frac{11}{7}\big] · \frac{7}{20}}$ =

= $\frac{\frac{1}{2}}{-\frac{10}{7} · \frac{7}{20}}$ =

= $\frac{\frac{1}{2}}{-\frac{1}{1} · \frac{1}{2}}$ =

= $\frac{\frac{1}{2}}{-\frac{1}{2}} = \frac{1}{2}·-2 = -1$