Dapnani 1 18.(5)-20.. 1. 2. 39 25 12 3. 20.3 3 1 +2 16. 4 4. 92 5. 53 5 3 6. 6-14 32 7. 57 6,9-1,5 8. 2,4

Решим примеры.

1. $$18 \cdot (\frac{1}{9})^2 - 20 \cdot \frac{1}{9} = 18 \cdot \frac{1}{81} - \frac{20}{9} = \frac{18}{81} - \frac{20}{9} = \frac{2}{9} - \frac{20}{9} = \frac{2-20}{9} = \frac{-18}{9} = -2$$

   Ответ: -2

2. $$\frac{3}{2} - \frac{9}{5} = \frac{3^{\scriptsize \text{×5}}}{2_{\scriptsize \text{×5}}} - \frac{9^{\scriptsize \text{×2}}}{5_{\scriptsize \text{×2}}} = \frac{15}{10} - \frac{18}{10} = \frac{15 - 18}{10} = \frac{-3}{10} = -0.3$$

   Ответ: -0.3

3. $$\frac{12}{20 \cdot 3} = \frac{12}{60} = \frac{1}{5} = 0.2$$

   Ответ: 0.2

4. $$(2 \frac{3}{4} + 2 \frac{1}{5}) \cdot 16 = (\frac{11}{4} + \frac{11}{5}) \cdot 16 = (\frac{11^{\scriptsize \text{×5}}}{4_{\scriptsize \text{×5}}} + \frac{11^{\scriptsize \text{×4}}}{5_{\scriptsize \text{×4}}}) \cdot 16 = (\frac{55}{20} + \frac{44}{20}) \cdot 16 = \frac{99}{20} \cdot 16 = \frac{99 \cdot 16}{20} = \frac{99 \cdot 4}{5} = \frac{396}{5} = 79.2$$

   Ответ: 79.2

5. $$\frac{9}{5} \cdot \frac{2}{3} = \frac{9 \cdot 2}{5 \cdot 3} = \frac{3 \cdot 2}{5} = \frac{6}{5} = 1.2$$

   Ответ: 1.2

6. $$\frac{5}{6} - \frac{3}{14} = \frac{5^{\scriptsize \text{×7}}}{6_{\scriptsize \text{×7}}} - \frac{3^{\scriptsize \text{×3}}}{14_{\scriptsize \text{×3}}} = \frac{35}{42} - \frac{9}{42} = \frac{35-9}{42} = \frac{26}{42} = \frac{13}{21} $$

   Ответ: 13/21

7. $$\frac{3}{5} - \frac{2}{7} = \frac{3^{\scriptsize \text{×7}}}{5_{\scriptsize \text{×7}}} - \frac{2^{\scriptsize \text{×5}}}{7_{\scriptsize \text{×5}}} = \frac{21}{35} - \frac{10}{35} = \frac{21-10}{35} = \frac{11}{35}$$

   Ответ: 11/35

8. $$\frac{6.9 - 1.5}{2.4} = \frac{5.4}{2.4} = \frac{54}{24} = \frac{9}{4} = 2.25$$

   Ответ: 2.25