Bài tập 2 trang 91 toán lớp 4 tập 2 Cánh diều:Tính:a) $\frac{2}{7} +\frac{3}{14}$$\frac{2}{3}...

{
"Câu trả lời 1": {
"a": "a) $\frac{2}{7} +\frac{3}{14} = \frac{4}{14} + \frac{3}{14} = \frac{7}{14} = \frac{1}{2}$; $\frac{2}{3} +\frac{1}{12} = \frac{8}{12} + \frac{1}{12} = \frac{9}{12} = \frac{3}{4}$; $8+\frac{7}{4} = 8 + 1\frac{3}{4} = 9\frac{3}{4}$; $\frac{6}{5} +4 = \frac{6}{5} + \frac{20}{5} = \frac{26}{5}$",
"b": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9}{16} - \frac{4}{16} = \frac{5}{16}$; $\frac{7}{3} -\frac{2}{9} = \frac{21}{9} - \frac{2}{9} = \frac{19}{9}$; $6 -\frac{3}{10} = 6 - 0\frac{3}{10} = 5\frac{7}{10}$; $\frac{18}{5} - 2 = \frac{18}{5} - \frac{10}{5} = \frac{8}{5}$",
"c": "c) $\frac{2}{3} \times \frac{4}{9} = \frac{8}{27}$; $\frac{7}{10} \times \frac{5}{2} = \frac{35}{20} = \frac{7}{4}$; $\frac{13}{14} \times 4 = \frac{52}{14} = \frac{26}{7}$; $5\times \frac{2}{7} = \frac{10}{7}$",
"d": "d) $\frac{8}{5} :\frac{2}{5} = \frac{8}{5} \times \frac{5}{2} = 2$; $\frac{6}{21} : \frac{3}{4} = \frac{6}{21} \times \frac{4}{3} = \frac{8}{21}$; $\frac{6}{13} :3 = \frac{6}{13} \div 3 = \frac{2}{13}$; $9:\frac{3}{8} = 9 \div \frac{3}{8} = 9 \times \frac{8}{3} = 24$"
},
"Câu trả lời 2": {
"a": "a) $\frac{2}{7} +\frac{3}{14} = \frac{4+3}{14} = \frac{7}{14} = \frac{1}{2}$; $\frac{2}{3} +\frac{1}{12} = \frac{8+1}{12} = \frac{9}{12} = \frac{3}{4}$; $8+\frac{7}{4} = 8 + 1\frac{3}{4} = 9\frac{3}{4}$; $\frac{6}{5} +4 = \frac{6+20}{5} = \frac{26}{5}$",
"b": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9-4}{16} = \frac{5}{16}$; $\frac{7}{3} -\frac{2}{9} = \frac{21-2}{9} = \frac{19}{9}$; $6 -\frac{3}{10} = 6 - 0\frac{3}{10} = 5\frac{7}{10}$; $\frac{18}{5} - 2 = \frac{18-10}{5} = \frac{8}{5}$",
"c": "c) $\frac{2}{3} \times \frac{4}{9} = \frac{2 \times 4}{3 \times 9} = \frac{8}{27}$; $\frac{7}{10} \times \frac{5}{2} = \frac{7 \times 5}{10 \times 2} = \frac{35}{20} = \frac{7}{4}$; $\frac{13}{14} \times 4 = \frac{13 \times 4}{14} = \frac{52}{14} = \frac{26}{7}$; $5\times \frac{2}{7} = \frac{5 \times 2}{7} = \frac{10}{7}$",
"d": "d) $\frac{8}{5} :\frac{2}{5} = \frac{8}{5} \div \frac{2}{5} = \frac{8}{5} \times \frac{5}{2} = 2$; $\frac{6}{21} : \frac{3}{4} = \frac{6}{21} \div \frac{3}{4} = \frac{6}{21} \times \frac{4}{3} = \frac{8}{21}$; $\frac{6}{13} :3 = \frac{6}{13} \div 3 = \frac{6}{13} \div \frac{3}{1} = \frac{6}{13} \times \frac{1}{3} = \frac{2}{13}$; $9:\frac{3}{8} = 9 \div \frac{3}{8} = 9 \times \frac{8}{3} = 24$"
},
"Câu trả lời 3": {
"a": "a) $\frac{2}{7} +\frac{3}{14} = \frac{4}{14} + \frac{3}{14} = \frac{7}{14} = \frac{1}{2}$; $\frac{2}{3} +\frac{1}{12} = \frac{8}{12} + \frac{1}{12} = \frac{9}{12} = \frac{3}{4}$; $8+\frac{7}{4} = \frac{32}{4} + \frac{7}{4} = \frac{39}{4}$; $\frac{6}{5} +4 = \frac{6}{5} + \frac{20}{5} = \frac{26}{5}$",
"b": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9}{16} - \frac{4}{16} = \frac{5}{16}$; $\frac{7}{3} -\frac{2}{9} = \frac{21}{9} - \frac{2}{9} = \frac{19}{9}$; $6 -\frac{3}{10} = 6 - 0\frac{3}{10} = 5\frac{7}{10}$; $\frac{18}{5} - 2 = \frac{18}{5} - \frac{10}{5} = \frac{8}{5}$",
"c": "c) $\frac{2}{3} \times \frac{4}{9} = \frac{2 \times 4}{3 \times 9} = \frac{8}{27}$; $\frac{7}{10} \times \frac{5}{2} = \frac{7 \times 5}{10 \times 2} = \frac{35}{20} = \frac{7}{4}$; $\frac{13}{14} \times 4 = \frac{13 \times 4}{14} = \frac{52}{14} = \frac{26}{7}$; $5\times \frac{2}{7} = \frac{5 \times 2}{7} = \frac{10}{7}$",
"d": "d) $\frac{8}{5} :\frac{2}{5} = \frac{8}{5} \div \frac{2}{5} = \frac{8}{5} \times \frac{5}{2} = 2$; $\frac{6}{21} : \frac{3}{4} = \frac{6}{21} \div \frac{3}{4} = \frac{6}{21} \times \frac{4}{3} = \frac{8}{21}$; $\frac{6}{13} :3 = \frac{6}{13} \div 3 = \frac{6}{13} \div \frac{3}{1} = \frac{6}{13} \times \frac{1}{3} = \frac{2}{13}$; $9:\frac{3}{8} = 9 \div \frac{3}{8} = 9 \times \frac{8}{3} = 24$"
}
}