a: \(\dfrac{1}{8}\cdot\dfrac{4}{5}:\dfrac{3}{5}=\dfrac{1}{10}\cdot\dfrac{5}{3}=\dfrac{1}{2\cdot3}=\dfrac{1}{6}\)

b: \(=\dfrac{8-3}{12}\cdot\dfrac{6}{5}=\dfrac{6}{12}=\dfrac{1}{2}\)

c: \(=\dfrac{24}{35}:\dfrac{32}{35}=\dfrac{3}{4}\)

d: =63/21+15/21-7/21=71/21

a \(\dfrac{1}{8}\times\dfrac{4}{5}\times\dfrac{10}{6}=\dfrac{1}{6}\)

b \(\left(\dfrac{8}{12}-\dfrac{3}{12}\right)\times\dfrac{6}{5}=\dfrac{5}{12}\times\dfrac{6}{5}=\dfrac{1}{2}\)

c \(\dfrac{24}{35}:\dfrac{32}{35}=\dfrac{24}{35}\times\dfrac{35}{32}=\dfrac{3}{4}\)

d \(\dfrac{63}{21}+\dfrac{15}{21}-\dfrac{7}{21}=\dfrac{71}{21}\)

a) 4 + 5/7 = .... 28/7 + 5/7=.33/7..............

    5/9 x 6/7 = ..10/21....

    3 - 7/5 =  15/5 - 7/5...8/5........

    3/5 x 4/8 = ..3/10....

b) 2 - 1/4 = .8/4 - 1/4...7/4...

    4 : 5/9 = ..4 x 9/5 = 36/5....

    2/9 x 3/5 = .....2/15.....

    3/8 : 4 = ......3/8 x 1/4 = 3/2.....

a) \(4+\dfrac{5}{7}=\dfrac{4}{1}+\dfrac{5}{7}=\dfrac{28}{7}+\dfrac{5}{7}=\dfrac{33}{7}\)

   \(\dfrac{5}{9}\times\dfrac{6}{7}=\dfrac{10}{21}\)

    \(3-\dfrac{7}{5}=\dfrac{3}{1}-\dfrac{7}{5}=\dfrac{15}{5}-\dfrac{7}{5}=\dfrac{8}{5}\)

    \(\dfrac{3}{5}\times\dfrac{4}{8}=\dfrac{12}{40}=\dfrac{3}{10}\)

b) \(2-\dfrac{1}{4}=\dfrac{2}{1}-\dfrac{1}{4}=\dfrac{8}{4}-\dfrac{1}{4}=\dfrac{7}{4}\)

    \(4:\dfrac{5}{9}=\dfrac{4}{1}:\dfrac{5}{9}=\dfrac{4}{1}\times\dfrac{9}{5}=\dfrac{36}{5}\)

    \(\dfrac{2}{9}\times\dfrac{3}{5}=\dfrac{6}{45}=\dfrac{2}{15}\)

     \(\dfrac{3}{8}:4=\dfrac{3}{8}:\dfrac{4}{1}=\dfrac{3}{8}\times\dfrac{1}{4}=\dfrac{3}{2}\)

a) \(\dfrac{6}{7}+\dfrac{7}{8}=\dfrac{48}{56}+\dfrac{49}{56}=\dfrac{97}{56}\)

b) \(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)

c) \(\dfrac{2}{3}.\dfrac{4}{9}=\dfrac{8}{27}\)

d) \(\dfrac{1}{5}:\dfrac{2}{7}=\dfrac{1}{5}.\dfrac{7}{2}=\dfrac{7}{10}\)

a: =48/56+49/56

=97/56

b: =12/15-10/15

=2/15

c: =(2*4)/(3*9)=8/27

d: =1/5*7/2=7/10

` 6/7 + 7/8 = 48/56 + 49/56 = 97/56`

` 4/5 - 2/3 = 12/15 - 10/15 = 2/15`

` 2/3 xx 4/9 = 8/27`

` 1/5 : 2/7 = 1/5 . 7/2 = 7/10`

a: \(=\dfrac{13}{3}+\dfrac{17}{6}=\dfrac{26}{6}+\dfrac{17}{6}=\dfrac{43}{6}\)

b: \(=7-\dfrac{8}{3}=\dfrac{21-8}{3}=\dfrac{13}{3}\)

c: \(=\dfrac{17}{7}\cdot\dfrac{7}{4}=\dfrac{17}{4}\)

d: \(=\dfrac{16}{3}:\dfrac{16}{5}=\dfrac{16}{3}\cdot\dfrac{5}{16}=\dfrac{5}{3}\)

a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)

\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)

\(=\dfrac{-1621}{126}\)

b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)

\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)

\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)

\(=-\dfrac{49}{20}\)

a, 5/6

b, 4/35

c, 0.6

5/6

4/35

0.6

=5/6

= 4/35

=0.6

\(a,=\dfrac{\sqrt{7}-5}{2}-\dfrac{3-\sqrt{7}}{2}+\dfrac{6\left(\sqrt{7}+2\right)}{3}-\dfrac{5\left(4-\sqrt{7}\right)}{9}\\ =\dfrac{\sqrt{7}-5-3+\sqrt{7}}{2}+2\sqrt{7}+4-\dfrac{20-5\sqrt{7}}{9}\\ =\dfrac{2\sqrt{7}-8}{2}+2\sqrt{7}+4-\dfrac{20-5\sqrt{7}}{9}\\ =\sqrt{7}-4+2\sqrt{7}+4-\dfrac{20-5\sqrt{7}}{9}\\ =\dfrac{27\sqrt{7}-20+5\sqrt{7}}{9}=\dfrac{32\sqrt{7}-20}{9}\)

\(b,=\dfrac{2\left(\sqrt{6}+2\right)}{2}+\dfrac{2\left(\sqrt{6}-2\right)}{2}+\dfrac{5\sqrt{6}}{6}\\ =\sqrt{6}+2+\sqrt{6}-2+\dfrac{5\sqrt{6}}{6}\\ =\dfrac{12\sqrt{6}+5\sqrt{6}}{6}=\dfrac{17\sqrt{6}}{6}\)

\(c,=\dfrac{\sqrt{3}+\sqrt{2}+\sqrt{5}-\sqrt{3}-\sqrt{2}+\sqrt{5}}{\left(\sqrt{3}+\sqrt{2}\right)^2-5}\\ =\dfrac{2\sqrt{5}}{5+2\sqrt{6}-5}=\dfrac{2\sqrt{5}}{2\sqrt{6}}=\dfrac{\sqrt{30}}{6}\)

Thực hiện phép tính:

a, 5/17 + -5/34 . 2/5=5/17 + -1/17=4/17

b, 1/2 . 5/6 + 2/3 . 3/4 =5/12 + 6/12 =11/12

c, ( -2/5 + 1/3 ) . ( 3/2 - 3/7 )=-1/15 . 15/14=1/14