`4/5 xx 3/7 + 4/5 xx 6/7 - 4/5 xx 4/14`

`= 4/5 xx ( 3/7 + 6/7-4/14)`

`= 4/5 xx 1`

`= 4/5`

= 4/5 x ( 3/7 + 6/7 - 4/14 )

= 4/5 x ( 3/7 + 6/7 - 2/7 )

= 4/5 x 7/7

= 4/5

\(\dfrac{4}{5}\times\dfrac{3}{7}\times\dfrac{4}{5}\times\dfrac{6}{7}\times\dfrac{4}{14}=\dfrac{4}{5}\times\dfrac{3}{7}+\dfrac{4}{5}\times\dfrac{6}{7}-\dfrac{4}{5}\times\dfrac{2}{7}=\dfrac{4}{5}\times\left(\dfrac{6}{7}+\dfrac{3}{7}-\dfrac{2}{7}\right)=\dfrac{4}{5}\)

=4/5 * (3/7+6/7-4/14)

=4/5*(6/14+12/14-4/14)

=4/5*12/14

=48/70

nha ban

8/1225

\(\frac{288}{1225}-\frac{8}{35}=\frac{8}{1225}\) nha bạn k mình nha

4/5x3/7+4/5+6/7x6/7-4/5x4/14

= ( 3/7 + 6/7 + 4/14) x 4/5 

= 11/7 x 4/5 

= 44/35

44/35

4/5x3/7+4/5+6/7x6/7-4/5x4/14 ⇒ ( 3/7 + 6/7 + 4/14) x 4/5 ⇒ 11/7 x 4/5 ⇒ 44/35

= 4/5 x ( 3/7 + 6/7 - 4/14 )

= 4/5 x ( 3/7 + 6/7 - 2/7 )

= 4/5 x 7/7

= 4/5

4/5 x 3/7 + 4/5 x 6/7 - 4/5 x 4/14

= 4/5 x ( 3/7 + 6/7 - 4/14)

= 4/5 x 1

= 4/5

4/5

\(\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}:7+\frac{6}{5}\)

\(=\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}\times\frac{1}{7}+\frac{6}{5}\)

\(=\frac{3}{5}\times\left(\frac{6}{7}+\frac{1}{7}\right)+\frac{6}{5}\)

\(=\frac{3}{5}\times1+\frac{6}{5}\)

\(=\frac{3}{5}+\frac{6}{5}=\frac{9}{5}\)

~ Hok tốt ~

\(\frac{29}{12}:\frac{1}{2}-\frac{5}{12}:\frac{1}{2}-\frac{1}{2}\)

\(=\left(\frac{29}{12}-\frac{5}{12}\right):\frac{1}{2}-\frac{1}{2}\)

\(=2:\frac{1}{2}-\frac{1}{2}\)

\(=4-\frac{1}{2}=\frac{7}{2}\)

~ Hok tốt ~

\(\frac{2}{15}\times\frac{4}{7}+\frac{4}{7}\times\frac{2}{3}+\frac{4}{7}:5\)

\(=\frac{2}{15}\times\frac{4}{7}+\frac{4}{7}\times\frac{2}{3}+\frac{4}{7}\times\frac{1}{5}\)

\(=\left(\frac{2}{15}+\frac{2}{3}+\frac{1}{5}\right)\times\frac{4}{7}\)

\(=1\times\frac{4}{7}=\frac{4}{7}\)

~ Hok tốt ~

a) \(1678\cdot24+77\cdot1678-1678=1678\left(24+77-1\right)=167800\)

b) Ta có: \(\dfrac{2}{5}+\dfrac{4}{11}+\dfrac{3}{5}+\dfrac{18}{11}+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{4}{11}+\dfrac{18}{11}\right)+\dfrac{1}{4}+\dfrac{1}{6}\)

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

\(=\dfrac{36}{12}+\dfrac{3}{12}+\dfrac{2}{12}=\dfrac{41}{12}\)

c) \(\dfrac{7}{9\cdot7}+\dfrac{7}{9\cdot4}-\dfrac{7}{9\cdot10}\)

\(=\dfrac{7}{9}\left(\dfrac{1}{7}+\dfrac{1}{4}-\dfrac{1}{10}\right)\)

\(=\dfrac{7}{9}\cdot\left(\dfrac{20}{140}+\dfrac{35}{140}-\dfrac{14}{140}\right)\)

\(=\dfrac{7}{9}\cdot\dfrac{41}{140}=\dfrac{41}{180}\)

A  =\(\frac{2}{5}\times\frac{4}{7}+\frac{3}{5}\times\frac{4}{7}\)  B = \(\frac{17}{13}\times\frac{12}{17}-\frac{4}{13}\times\frac{12}{17}\)   C = \(\frac{9}{14}:\frac{6}{7}+\frac{5}{14}:\frac{6}{7}\)  D =\(\frac{9}{12}:\frac{7}{9}\times\frac{12}{19}\)

=  \(\frac{4}{7}\times\left(\frac{2}{5}+\frac{3}{5}\right)\)              =\(\left(\frac{17}{13}-\frac{4}{13}\right)\times\frac{12}{17}\)                = \((\frac{9}{14}+\frac{5}{14}):\frac{6}{7}\)         = \(\frac{9}{12}\times\frac{9}{7}\times\frac{12}{19}\)

=\(\frac{4}{7}\times1\)                                     = \(1\times\frac{12}{17}\)                                       = \(1:\frac{6}{7}\)                               = \(\frac{9\times9\times12}{12\times7\times19}\)

=\(\frac{4}{7}\)                                              =  \(\frac{12}{17}\)                                                =\(\frac{7}{6}\)                                    = \(\frac{9\times9}{7\times19}=\frac{81}{133}\)

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