Question

[nguyễn trọng kiên]

4/7+3/4+2/7

1/6+5/24+2/3

1/2+5/16-1/4

1-(1/5+1/2)

2/3+1/2-5/6

5/12+5/6-3/4

7/5-4/15-2/3

Answer 1

[subjects]

\(\dfrac{4}{7}+\dfrac{3}{4}+\dfrac{2}{7}\\ =\dfrac{6}{7}+\dfrac{3}{4}\\ =\dfrac{24}{28}+\dfrac{21}{28}=\dfrac{45}{28}\\ ------------\\ \dfrac{1}{6}+\dfrac{5}{24}+\dfrac{2}{3}\\ =\dfrac{4}{24}+\dfrac{5}{24}+\dfrac{16}{24}=\dfrac{25}{24}\\ ---------\\ \dfrac{1}{2}+\dfrac{5}{16}-\dfrac{1}{4}\\ =\dfrac{8}{16}+\dfrac{5}{16}-\dfrac{4}{16}=\dfrac{9}{16}\)

\(----------\\ 1-\left(\dfrac{1}{5}+\dfrac{1}{2}\right)\\ =\dfrac{10}{10}-\dfrac{2}{10}-\dfrac{5}{10}=\dfrac{3}{10}\\ ---------\\ \dfrac{2}{3}+\dfrac{1}{2}-\dfrac{5}{6}\\ =\dfrac{4}{6}+\dfrac{3}{6}-\dfrac{5}{6}=\dfrac{2}{6}=\dfrac{1.}{3}\\ --------\\ \dfrac{5}{12}+\dfrac{5}{6}-\dfrac{3}{4}\\ =\dfrac{5}{12}+\dfrac{10}{12}-\dfrac{9}{12}=\dfrac{6}{12}=\dfrac{1}{2}\\ ---------\)

\(\dfrac{7}{5}-\dfrac{4}{15}-\dfrac{2}{3}\\ =\dfrac{21}{15}-\dfrac{4}{15}-\dfrac{10}{15}=\dfrac{7}{15}\)

Answer 2

[HT.Phong (9A5)]

\(\dfrac{4}{7}+\dfrac{3}{4}+\dfrac{2}{7}=\left(\dfrac{4}{7}+\dfrac{2}{7}\right)+\dfrac{3}{4}=\dfrac{6}{7}+\dfrac{3}{4}=\dfrac{24}{28}+\dfrac{21}{28}=\dfrac{45}{28}\)

\(\dfrac{1}{6}+\dfrac{5}{24}+\dfrac{2}{3}=\dfrac{4}{24}+\dfrac{5}{24}+\dfrac{16}{24}=\dfrac{25}{24}\)

\(\dfrac{1}{2}+\dfrac{5}{16}-\dfrac{1}{4}=\dfrac{8}{16}+\dfrac{5}{16}-\dfrac{4}{16}=\dfrac{9}{16}\)

\(1-\left(\dfrac{1}{5}+\dfrac{1}{2}\right)=1-\left(\dfrac{2}{10}+\dfrac{5}{10}\right)=1-\dfrac{7}{10}=\dfrac{10}{10}-\dfrac{7}{10}=\dfrac{3}{10}\)

\(\dfrac{2}{3}+\dfrac{1}{2}-\dfrac{5}{6}=\dfrac{4}{6}+\dfrac{3}{6}-\dfrac{5}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)

\(\dfrac{5}{12}+\dfrac{5}{6}-\dfrac{3}{4}=\dfrac{5}{12}+\dfrac{10}{12}-\dfrac{9}{12}=\dfrac{6}{12}=\dfrac{1}{2}\)

\(\dfrac{7}{5}-\dfrac{4}{15}-\dfrac{2}{3}=\dfrac{21}{15}-\dfrac{4}{15}-\dfrac{10}{15}=\dfrac{7}{15}\)