Tính hợp lý: a) \( \frac{5}{15} + \frac{14}{25} - \frac{12}{9} + \frac{2}{7} + \frac{11}{25} \) b) \( \frac{3}{7} \cdot \frac{1}{5} + 4,2 + \frac{4}{7} + \frac{3}{7} \cdot \frac{2}{5} + 2,8 - \frac{4}{7} \) c) \( \left( -\frac{7}{5} \right) \cdot 2 \cdot \frac{2}{3} - 1 \cdot \frac{2}{5} - \left( -\frac{2}{3} \right) \) d) \( \left( \frac{2}{7} - \frac{9}{4} \right) - \left( -\frac{3}{7} + \frac{5}{4} \right) - \left( -\frac{2}{4} - \frac{9}{7} \right) \)
----- Nội dung ảnh -----
Bài 2. Tính hợp lý:
a) \( \frac{5}{15} + \frac{14}{25} - \frac{12}{9} + \frac{2}{7} + \frac{11}{25} \)
b) \( \frac{3}{7} \cdot \frac{1}{5} + 4,2 + \frac{4}{7} + \frac{3}{7} \cdot \frac{2}{5} + 2,8 - \frac{4}{7} \)
c) \( \left( -\frac{7}{5} \right) \cdot 2 \cdot \frac{2}{3} - 1 \cdot \frac{2}{5} - \left( -\frac{2}{3} \right) \)
d) \( \left( \frac{2}{7} - \frac{9}{4} \right) - \left( -\frac{3}{7} + \frac{5}{4} \right) - \left( -\frac{2}{4} - \frac{9}{7} \right) \)