Bài tập 2 trang 99 vở bài tập (VBT) toán lớp 4 tập 2 Cánh diềuTính:a)...

{
"content1": {
"a": {
"1": "a) $\frac{2}{7}+\frac{3}{14} = \frac{4}{14}+\frac{3}{14} = \frac{7}{14} = \frac{1}{2}$",
"2": "$\frac{2}{3}+\frac{1}{12} = \frac{8}{12}+\frac{1}{12} = \frac{9}{12} = \frac{3}{4}$",
"3": "$8+\frac{7}{4} = 8+1\frac{3}{4} = 9\frac{3}{4}$",
"4": "$\frac{6}{5}+4 = 1\frac{1}{5}+4 = 5\frac{1}{5}$"
},
"b": {
"1": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9}{16}-\frac{4}{16} = \frac{5}{16}$",
"2": "$\frac{7}{3}-\frac{2}{9} = \frac{21}{9}-\frac{2}{9} = \frac{19}{9}$",
"3": "$6-\frac{3}{10} = 6-0.3 = 5.7$",
"4": "$\frac{18}{5}-2 = \frac{18}{5}-\frac{10}{5} = \frac{8}{5}$"
},
"c": {
"1": "c) $\frac{2}{3}\times \frac{4}{9} = \frac{8}{27}$",
"2": "$\frac{7}{10}\times \frac{5}{2} = \frac{7}{4} = 1\frac{3}{4}$",
"3": "$\frac{13}{14}\times 4 = \frac{13}{14}\times \frac{56}{14} = 4$",
"4": "$5\times \frac{2}{7} = \frac{10}{7}$"
},
"d": {
"1": "d) $\frac{8}{5}:\frac{2}{5} = \frac{8}{5}\div \frac{2}{5} = \frac{8}{5}\times \frac{5}{2} = 2$",
"2": "$\frac{6}{21}:\frac{3}{4} = \frac{2}{7}:\frac{3}{4} = \frac{8}{21} = \frac{8}{21}$",
"3": "$\frac{6}{13}:3 = \frac{6}{13}\div 3 = \frac{6}{39} = \frac{2}{13}$",
"4": "$9:\frac{3}{8} = 9\div \frac{3}{8} = 9\times \frac{8}{3} = 24$"
}
},
"content2": {
"a": {
"1": "a) $\frac{2}{7}+\frac{3}{14} = \frac{2\times 2 + 3}{14} = \frac{7}{14} = \frac{1}{2}$",
"2": "$\frac{2}{3}+\frac{1}{12} = \frac{2\times 4 + 1}{12} = \frac{9}{12} = \frac{3}{4}$",
"3": "$8+\frac{7}{4} = 8 + 1\frac{3}{4} = 9\frac{3}{4}$",
"4": "$\frac{6}{5}+4 = 1\frac{1}{5}+4 = 5\frac{1}{5}$"
},
"b": {
"1": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9}{16}-\frac{4}{16} = \frac{5}{16}$",
"2": "$\frac{7}{3}-\frac{2}{9} = \frac{7\times 3 - 2}{9} = \frac{21 - 2}{9} = \frac{19}{9}$",
"3": "$6-\frac{3}{10} = 6 - 0.3 = 5.7$",
"4": "$\frac{18}{5}-2 = \frac{18}{5} - \frac{10}{5} = \frac{8}{5}$"
},
"c": {
"1": "c) $\frac{2}{3}\times \frac{4}{9} = \frac{2\times 4}{3\times 9} = \frac{8}{27}$",
"2": "$\frac{7}{10}\times \frac{5}{2} = \frac{7\times 5}{10\times 2} = \frac{35}{20} = 1\frac{3}{4}$",
"3": "$\frac{13}{14}\times 4 = \frac{13\times 4}{14} = 4$",
"4": "$5\times \frac{2}{7} = 5\times \frac{2}{7} = \frac{10}{7}$"
},
"d": {
"1": "d) $\frac{8}{5}:\frac{2}{5} = \frac{8}{5} / \frac{2}{5} = \frac{8}{5} \times \frac{5}{2} = 2$",
"2": "$\frac{6}{21}:\frac{3}{4} = \frac{6}{21} / \frac{3}{4} = \frac{6}{21} \times \frac{4}{3} = \frac{8}{21}$",
"3": "$\frac{6}{13}:3 = \frac{6}{13} / 3 = \frac{6}{39} = \frac{2}{13}$",
"4": "$9:\frac{3}{8} = 9 / \frac{3}{8} = 9 \times \frac{8}{3} = 24$"
}
},
"content3": {
"a": {
"1": "a) $\frac{2}{7}+\frac{3}{14} = \frac{4+3}{14} = \frac{7}{14} = \frac{1}{2}$",
"2": "$\frac{2}{3}+\frac{1}{12} = \frac{8+1}{12} = \frac{9}{12} = \frac{3}{4}$",
"3": "$8+\frac{7}{4} = 8+1\frac{3}{4} = 9\frac{3}{4}$",
"4": "$\frac{6}{5}+4 = 1\frac{1}{5}+4 = 5\frac{1}{5}$"
},
"b": {
"1": "b) $\frac{9}{16}-\frac{1}{4} = \frac{9-4}{16} = \frac{5}{16}$",
"2": "$\frac{7}{3}-\frac{2}{9} = \frac{21-2}{9} = \frac{19}{9}$",
"3": "$6-\frac{3}{10} = 6-0.3 = 5.7$",
"4": "$\frac{18}{5}-2 = \frac{18-10}{5} = \frac{8}{5}$"
},
"c": {
"1": "c) $\frac{2}{3}\times \frac{4}{9} = \frac{2\times 4}{3\times 9} = \frac{8}{27}$",
"2": "$\frac{7}{10}\times \frac{5}{2} = \frac{7\times 5}{10\times 2} = \frac{35}{20} = 1\frac{3}{4}$",
"3": "$\frac{13}{14}\times 4 = \frac{13\times 4}{14} = 4$",
"4": "$5\times \frac{2}{7} = 5\times \frac{2}{7} = \frac{10}{7}$"
},
"d": {
"1": "d) $\frac{8}{5}:\frac{2}{5} = \frac{8}{5}\div \frac{2}{5} = \frac{8}{5}\times \frac{5}{2} = 2$",
"2": "$\frac{6}{21}:\frac{3}{4} = \frac{6}{21}\div \frac{3}{4} = \frac{6}{21}\times \frac{4}{3} = \frac{8}{21}$",
"3": "$\frac{6}{13}:3 = \frac{6}{13}\div 3 = \frac{6}{39} = \frac{2}{13}$",
"4": "$9:\frac{3}{8} = 9\div \frac{3}{8} = 9\times \frac{8}{3} = 24$"
}
}
}