5. Приведите дроби к общему знаменателю и сложите их. 1) a) 1/4+1/3 6) 1/5+1/2 B) 1/3+1/7 2) a) 2/3+5/9 6) 3/8+1/2 B) 1/14+3/7

Ответ:

1. 1) a) \(\frac{1}{4} + \frac{1}{3} = \frac{1 \cdot 3}{4 \cdot 3} + \frac{1 \cdot 4}{3 \cdot 4} = \frac{3}{12} + \frac{4}{12} = \frac{3+4}{12} = \frac{7}{12}\)
2. 6) \(\frac{1}{5} + \frac{1}{2} = \frac{1 \cdot 2}{5 \cdot 2} + \frac{1 \cdot 5}{2 \cdot 5} = \frac{2}{10} + \frac{5}{10} = \frac{2+5}{10} = \frac{7}{10}\)
3. B) \(\frac{1}{3} + \frac{1}{7} = \frac{1 \cdot 7}{3 \cdot 7} + \frac{1 \cdot 3}{7 \cdot 3} = \frac{7}{21} + \frac{3}{21} = \frac{7+3}{21} = \frac{10}{21}\)
4. 2) a) \(\frac{2}{3} + \frac{5}{9} = \frac{2 \cdot 3}{3 \cdot 3} + \frac{5}{9} = \frac{6}{9} + \frac{5}{9} = \frac{6+5}{9} = \frac{11}{9} = 1\frac{2}{9}\)
5. 6) \(\frac{3}{8} + \frac{1}{2} = \frac{3}{8} + \frac{1 \cdot 4}{2 \cdot 4} = \frac{3}{8} + \frac{4}{8} = \frac{3+4}{8} = \frac{7}{8}\)
6. B) \(\frac{1}{14} + \frac{3}{7} = \frac{1}{14} + \frac{3 \cdot 2}{7 \cdot 2} = \frac{1}{14} + \frac{6}{14} = \frac{1+6}{14} = \frac{7}{14} = \frac{1}{2}\)

Ответ: