\(=\dfrac{5}{9}\times\dfrac{7}{4}+\dfrac{13}{9}\times\dfrac{7}{4}=\dfrac{7}{4}\times\left(\dfrac{5}{9}+\dfrac{13}{9}\right)=\dfrac{7}{4}\times2=\dfrac{7}{2}\)

=\(\dfrac{5}{9}\)x\(\dfrac{7}{4}+\dfrac{13}{9}\)x\(\dfrac{7}{4}\)
=\(\dfrac{7}{4}\)x\(\left(\dfrac{5}{9}+\dfrac{13}{9}\right)\)
=\(\dfrac{7}{4}\)x\(2\)
=\(\dfrac{7}{2}\)

\(a.14,52\div1,5-9,81\div1,5\)

\(=\left(14,52-9,81\right)\div1,5\)

\(=4,71\div1,5=3,14\)

\(b.\frac{5}{9}:\frac{4}{7}+\frac{13}{9}\times\frac{7}{4}\)

\(=\frac{5}{9}\times\frac{7}{4}+\frac{13}{9}\times\frac{7}{4}\)

\(=\left(\frac{5}{9}+\frac{13}{9}\right)\times\frac{7}{4}\)

\(=\frac{18}{9}\times\frac{7}{4}\)

\(=2\times\frac{7}{4}\)

\(=\frac{7}{2}\)

14,52:1,5-9,81:1,5=( 14,52-9,81 ) : 1,5

=4,71:1,5

=3,14

con thứ 2 thì mình chịu, bạn tự làm nha.

học tốt lên nhé.  mình chỉ biết làm luôn thôi nhé.

   \(\frac{7}{4}\times\frac{15}{7}+\frac{13}{7}\times\frac{9}{4}-\frac{2}{7}\)

\(=\left(\frac{7}{4}+\frac{9}{4}\right)\times\left(\frac{15}{7}+\frac{13}{7}\right)-\frac{2}{7}\)

\(=4\times4-\frac{2}{7}\)

\(=16-\frac{2}{7}\)

\(=\frac{112}{7}-\frac{2}{7}\)

\(=\frac{110}{7}\)

`4/6+7/13+17/9+19/13+1/9+14/6`

`=(4/6+14/6)+(7/13+19/13)+(17/9+1/9)`

`=18/6+26/13+18/9`

`=3+2+2`

`=7`

sửa hộ cái lớp cái !

=(3/7+4/7)+(4/9+5/9)

=1+1=2

\(\dfrac{3}{7}+\dfrac{4}{9}+\dfrac{4}{7}+\dfrac{5}{9}=\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{7}{7}+\dfrac{9}{9}=1+1=2\)

a, = \(\frac{11}{21}\)x \(\left(\frac{7}{4}+\frac{5}{4}\right)\)

   = \(\frac{11}{21}\)x 3

  = \(\frac{33}{21}\)

b) = \(\left(\frac{23}{14}-\frac{9}{14}\right)\)x \(\frac{6}{13}\)

    = 1 x \(\frac{6}{13}\)

    = \(\frac{6}{13}\)

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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 =\(\frac{9}{12}:\frac{7}{9}\times\frac{12}{19}\)

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

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

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

   -  

   \(\frac{5}{9}:\frac{4}{7}+\frac{13}{9}.\frac{7}{4}\)

= \(\frac{5}{9}.\frac{7}{4}+\frac{13}{9}.\frac{7}{4}\)

= \(\left(\frac{5}{9}+\frac{13}{9}\right).\frac{7}{4}\)

=\(\frac{18}{9}.\frac{7}{4}\)

=2.7/4 = 7/2

\(\frac{5}{9}:\frac{4}{7}+\frac{13}{9}.\frac{7}{4}\)

\(=\frac{5}{9}.\frac{7}{4}+\frac{13}{9}.\frac{7}{4}\)

\(=\frac{7}{4}.\left(\frac{5}{9}+\frac{13}{9}\right)\)

\(=\frac{7}{4}.2\)

\(=\frac{7}{2}\)

Chúc bạn học tốt ~