2. Найдите значение выражения: a)-29 + 12 + (-40) + (−31) + 38; 6 5 13 6)-13.4명이 11 в) -15 4,2-4,2

Ответ: а) -50; б) -10; в) 0

а) -29 + 12 + (-40) + (-31) + 38 = -29 + 12 - 40 - 31 + 38 = -17 - 40 - 31 + 38 = -57 - 31 + 38 = -88 + 38 = -50

б) -13\(\frac{6}{6}\) \(\cdot\) 4\(\frac{5}{13}\) = -\(\frac{13 \cdot 6 + 6}{6}\) \(\cdot\) \(\frac{4 \cdot 13 + 5}{13}\) = -\(\frac{84}{6}\) \(\cdot\) \(\frac{57}{13}\) = -\(\frac{14}{1}\) \(\cdot\) \(\frac{19}{13}\) = -\(\frac{266}{13}\) = -\(\frac{260 + 6}{13}\) = -20\(\frac{6}{13}\)

в) \(\frac{11}{15}\) \(\cdot\) 4,2 - 4,2 = 4,2 \(\cdot\) (\(\frac{11}{15}\) - 1) = 4,2 \(\cdot\) (\(\frac{11}{15}\) - \(\frac{15}{15}\)) = 4,2 \(\cdot\) (\(\frac{-4}{15}\)) = \(\frac{42}{10}\) \(\cdot\) (\(\frac{-4}{15}\)) = \(\frac{21}{5}\) \(\cdot\) (\(\frac{-2}{15}\)) = \(\frac{7}{1}\) \(\cdot\) (\(\frac{-2}{5}\)) = \(\frac{-14}{5}\) = -2.8

Ответ: а) -50; б) -10; в) 0