Вариант 2. №1. Вычислите:

Решение:

1. \( 2\frac{3}{5} \cdot \frac{25}{26} + 2\frac{1}{4} \cdot \frac{27}{16} - 3\frac{5}{6} \)
• \( \frac{13}{5} \cdot \frac{25}{26} = \frac{13 \cdot 25}{5 \cdot 26} = \frac{1 \cdot 5}{1 \cdot 2} = \frac{5}{2} \)
• \( \frac{9}{4} \cdot \frac{27}{16} = \frac{243}{64} \)
• \( \frac{5}{2} + \frac{243}{64} = \frac{5 \cdot 32}{64} + \frac{243}{64} = \frac{160 + 243}{64} = \frac{403}{64} \)
• \( \frac{403}{64} - 3\frac{5}{6} = \frac{403}{64} - \frac{23}{6} = \frac{403 \cdot 3 - 23 \cdot 32}{192} = \frac{1209 - 736}{192} = \frac{473}{192} \)
2. \( -2.4 \cdot 3 + 0.21:0.07 + 15 \cdot (-0.3) + 9.7 \)
• \( -7.2 + 3 + (-4.5) + 9.7 \)
• \( -7.2 + 3 - 4.5 + 9.7 \)
• \( -11.7 + 12.7 = 1 \)
3. \( 8 + |4 - 52| - 2 \cdot |4.3 + 9.7| \)
• \( 8 + |-48| - 2 \cdot |14| \)
• \( 8 + 48 - 2 \cdot 14 \)
• \( 56 - 28 = 28 \)

Ответ: 1) \( \frac{473}{192} \); 2) 1; 3) 28.