№1. Вычислите: 1)+; 2) -; 3) 18인 4) 729-36

Ответ: 1) 9/8; 2) 29/40; 3) 1/3; 4) 17/24

1) \(\frac{3}{4} + \frac{3}{8} = \frac{3 \cdot 2}{4 \cdot 2} + \frac{3}{8} = \frac{6}{8} + \frac{3}{8} = \frac{6+3}{8} = \frac{9}{8}\)

2) \(\frac{7}{8} - \frac{3}{20} = \frac{7 \cdot 5}{8 \cdot 5} - \frac{3 \cdot 2}{20 \cdot 2} = \frac{35}{40} - \frac{6}{40} = \frac{35-6}{40} = \frac{29}{40}\)

3) \(\frac{17}{18} - \frac{2}{3} + \frac{1}{6} = \frac{17}{18} - \frac{2 \cdot 6}{3 \cdot 6} + \frac{1 \cdot 3}{6 \cdot 3} = \frac{17}{18} - \frac{12}{18} + \frac{3}{18} = \frac{17-12+3}{18} = \frac{8}{18} = \frac{4}{9}\)

4) \(\frac{49}{72} + \frac{8}{9} - \frac{23}{36} = \frac{49}{72} + \frac{8 \cdot 8}{9 \cdot 8} - \frac{23 \cdot 2}{36 \cdot 2} = \frac{49}{72} + \frac{64}{72} - \frac{46}{72} = \frac{49+64-46}{72} = \frac{67}{72}\)

Ответ: 1) 9/8; 2) 29/40; 3) 1/3; 4) 17/24