5.88 Упростите выражение: 1 a) 흙a - (a-1); 27 4 9 3 1 6) (7a - 7) -9(2+); 1) (0,98 б) 5 7 5 3 5 9 ;

a) \[ \frac{1}{27}a - (\frac{4}{9}a - \frac{1}{3}a) = \frac{1}{27}a - \frac{4}{9}a + \frac{1}{3}a = \frac{1}{27}a - \frac{12}{27}a + \frac{9}{27}a = (\frac{1 - 12 + 9}{27})a = \frac{-2}{27}a = -\frac{2}{27}a\\ \]

б) \[ \frac{5}{7}(\frac{7}{5}a - 7) - 9(2\frac{1}{3}a + \frac{5}{9}) = \frac{5}{7} \cdot \frac{7}{5}a - \frac{5}{7} \cdot 7 - 9(\frac{7}{3}a + \frac{5}{9}) = a - 5 - 9 \cdot \frac{7}{3}a - 9 \cdot \frac{5}{9} = a - 5 - 21a - 5 = -20a - 10 \]