Giải Bài tập 2 trang 91 Toán 4 tập 2 Cánh diều

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) $\frac{9}{16}-\frac{1}{4}=\frac{9}{16}-\frac{4}{16}=\frac{5}{16}$

$\frac{7}{3} -\frac{2}{9}=\frac{21}{9}-\frac{2}{9}=\frac{19}{9}$

$6 -\frac{3}{10}=\frac{60}{10}-\frac{3}{10}=\frac{57}{10}$

$\frac{18}{5} - 2=\frac{18}{5}-\frac{10}{5}=\frac{8}{5}$

c) $\frac{2}{3} \times \frac{4}{9}=\frac{8}{27}$

$\frac{7}{10} \times \frac{5}{2}=\frac{35}{20}=\frac{7}{10}$

$\frac{13}{14} \times 4=\frac{52}{14}=\frac{26}{7}$

$5\times \frac{2}{7}=\frac{10}{7}$

d) $\frac{8}{5} :\frac{2}{5}=\frac{8}{5} \times \frac{5}{2}=\frac{40}{10}=4$

$\frac{6}{21} : \frac{3}{4}=\frac{6}{21} \times \frac{4}{3} = \frac{24}{63} = \frac{8}{21}$

$\frac{6}{13} :3=\frac{6}{13} \times \frac{1}{3}=\frac{6}{39}=\frac{2}{13}$

$9:\frac{3}{8}=9 \times \frac{8}{3}=\frac{72}{3}=24$