a) 

\(\Rightarrow\dfrac{47}{10}.x=\dfrac{1}{5}+\dfrac{2}{3}\)

\(\Rightarrow\dfrac{47}{10}.x=\dfrac{3}{15}+\dfrac{10}{15}\)

\(\Rightarrow\dfrac{47}{10}.x=\dfrac{13}{15}\)

\(\Rightarrow x=\dfrac{13}{15}:\dfrac{47}{10}\)

\(\Rightarrow x=\dfrac{13}{10}.\dfrac{10}{47}\)

\(\Rightarrow x=\dfrac{13}{47}\)

b)

\(\Rightarrow\dfrac{5}{7}:x=\dfrac{1}{6}-\dfrac{4}{5}\)

\(\Rightarrow\dfrac{5}{7}:x=\dfrac{5}{30}-\dfrac{24}{30}\)

\(\Rightarrow\dfrac{5}{7}:x=-\dfrac{19}{30}\)

\(\Rightarrow x=\dfrac{5}{7}:\left(-\dfrac{19}{30}\right)\)

\(\Rightarrow x=\dfrac{5}{7}.\left(-\dfrac{30}{19}\right)\)

\(\Rightarrow x=-\dfrac{150}{133}\)

a,Cách 1:     (6/11 + 5/11 ) x 3/7                                             Cách 2 :(6/11 + 5/11) x 3/7

                 =       1     x 3/7                                                              =6/11 x 3/7  + 5/11 x 3/7

                  =            3/7                                                                  =      18/77   +     15/77 

                                                                                                      =                3/7

b, Cách 1:3/5 x 7/9 -  3/5 x 2/9                                               Cách 2 :3/5 x 7/9 - 3/5 x 2/9

            =    7/15    -       2/15                                                           = 3/5 x (7/9 - 2/9 )    

            =             1/3                                                                      = 3/5  x     5/9

                                                                                                      =       1/3

c, Cách 1:(6/7 - 4/7) : 2/5                                                      Cách 2: ( 6/7- 4/7 ) : 2/5 

             =     2/7     :  2/5                                                                =     6/7 : 2/5 - 4/7 : 2/5

            =         5/7                                                                         =       15/7    -       10/7  

                                                                                                    =                5/7

d,Cách 1:8/15 : 2/11 + 7/15 : 2/11                                         Cách 2:8/15 : 2/11 +7/15 : 2/11

            =  88/30       +     77/30                                                      =(8/15+7/15) :2/11

            =            11/2                                                                    =   1   :      2/11

                                                                                                    =        11/2

Bài 2 cậu tự làm nhé !                                                             

\(2a.160\)

\(b.2\)

\(c.\frac{8064}{5}\)

\(d.\frac{1}{3}\)

A) ( 2/5× 1/2)×3/8 =?

B)7/9 ×3/5 + 4/9 ÷3/5=?

a \(\dfrac{2}{3}x+\dfrac{1}{3}=\dfrac{1}{5}\\ \dfrac{2}{3}x=\dfrac{1}{5}-\dfrac{1}{3}\\ \dfrac{2}{3}x=\dfrac{-2}{15}\\ x=-\dfrac{2}{15}:\dfrac{2}{3}\\ x=-\dfrac{1}{5}\)   b) \(\dfrac{4}{5}-\dfrac{5}{3}x=-2\\ \dfrac{5}{3}x=\dfrac{4}{5}+2\\ \dfrac{5}{3}x=\dfrac{14}{5}\\ x=\dfrac{14}{5}:\dfrac{5}{3}\\ x=\dfrac{42}{25}\)c) \(\dfrac{1}{5}+\dfrac{5}{3}:x=\dfrac{1}{2}\\ \dfrac{5}{3}:x=\dfrac{1}{2}-\dfrac{1}{5}\\ \dfrac{5}{3}:x=\dfrac{3}{10}\\ x=\dfrac{5}{3}:\dfrac{3}{10}\\ x=\dfrac{50}{9}\)d) \(\dfrac{5}{7}:x-3=-\dfrac{2}{7}\\ \dfrac{5}{7}:x=3-\dfrac{2}{7}\\ \dfrac{5}{7}:x=\dfrac{19}{7}\\ x=\dfrac{5}{7}:\dfrac{19}{7}\\ x=\dfrac{5}{19}\)

a: =2/5-3/5+3/7=3/7-1/5

=15/35-7/35

=8/35

b: =>5/7:x=4/3

=>x=5/7:4/3=5/7*3/4=15/28

c: =>x-1/3=15/8:4/5=15/8*5/4=75/32

=>x=75/32+1/3=257/96

d: =>2x+1/8=2/7

=>2x=9/56

=>x=9/112

e: =>2x=10/3-5/4-3/4=10/3-2=4/3

=>x=2/3

\(a,\dfrac{2}{5}+\dfrac{3}{7}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{5}+\dfrac{3}{7}-\dfrac{3}{5}\\=\left(\dfrac{2}{5}-\dfrac{3}{5}\right)+\dfrac{3}{7}\\ =-\dfrac{1}{5}+\dfrac{3}{7}\\ =-\dfrac{7}{35}+\dfrac{15}{35}\\ =\dfrac{8}{35}\\ b,1-\dfrac{5}{7}:x=-\dfrac{1}{3}\\ =>\dfrac{5}{7}:x=1-\left(-\dfrac{1}{3}\right)\\ =>\dfrac{5}{7}:x=1+\dfrac{1}{3}\\ =>\dfrac{5}{7}:x=\dfrac{3}{3}+\dfrac{1}{3}\\ =>\dfrac{5}{7}:x=\dfrac{4}{3}\\ =>x=\dfrac{5}{7}:\dfrac{4}{3}\\ =>x=\dfrac{5}{7}.\dfrac{3}{4}\\ =>x=\dfrac{15}{28}\\ c,\dfrac{4}{5}\left(x-\dfrac{1}{3}\right)=\dfrac{15}{8}\\ =>x-\dfrac{1}{3}=\dfrac{15}{8}:\dfrac{4}{5}\\ =>x-\dfrac{1}{3}=\dfrac{15}{8}.\dfrac{5}{4}\\ =>x-\dfrac{1}{3}=\dfrac{75}{32}\\ =>x=\dfrac{75}{32}+\dfrac{1}{3}\\ =>x=\dfrac{257}{96}\)

\(d,\dfrac{2}{3}:\left(2x+\dfrac{1}{8}\right)=\dfrac{7}{3}\\ =>2x+\dfrac{1}{8}=\dfrac{2}{3}:\dfrac{7}{3}\\ =>2x+\dfrac{1}{8}=\dfrac{2}{3}.\dfrac{3}{7}\\ =>2x+\dfrac{1}{8}=\dfrac{2}{7}\\ =>2x=\dfrac{2}{7}-\dfrac{1}{8}\\ =>2x=\dfrac{16}{56}-\dfrac{7}{56}\\ =>2x=\dfrac{9}{56}\\ =>x=\dfrac{9}{56}:2\\ =>x=\dfrac{9}{112}\\ e,2x+\dfrac{3}{4}=\dfrac{10}{3}-\dfrac{5}{4}\\ =>e,2x+\dfrac{3}{4}=\dfrac{40}{12}-\dfrac{15}{12}\\ =>2x+\dfrac{3}{4}=\dfrac{25}{12}\\ =>2x=\dfrac{25}{12}-\dfrac{3}{4}\\ =>2x=\dfrac{25}{12}-\dfrac{9}{12}\\ =>2x=\dfrac{16}{12}\\ =>2x=\dfrac{4}{3}\\ =>x=\dfrac{4}{3}:2\\ =>x=\dfrac{4}{6}\\ =>x=\dfrac{2}{3}\)

a) \(x+\dfrac{1}{2}=\dfrac{3}{5}\)

    \(x=\dfrac{3}{5}-\dfrac{1}{2}\) 

    \(x=\dfrac{6}{10}-\dfrac{5}{10}\)

    \(x=\dfrac{1}{10}\)

b) \(x\times\dfrac{6}{7}=\dfrac{5}{21}\)

    \(x=\dfrac{5}{21}:\dfrac{6}{7}\)

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

    \(x=\dfrac{5}{18}\)

c) \(x:\dfrac{4}{3}=\dfrac{8}{9}\)

    \(x=\dfrac{8}{9}\times\dfrac{4}{3}\)

   \(x=\dfrac{32}{27}\)

a: x=3/5-1/2=6/10-5/10=1/10

b: x=5/21:6/7=5/21x7/5=35/105=1/3

c: x=8/9x4/3=32/27

\(a.x+\dfrac{1}{2}=\dfrac{3}{5}\)

\(x=\dfrac{3}{5}-\dfrac{1}{2}=\dfrac{1}{10}\)

\(b.x\times\dfrac{6}{7}=\dfrac{5}{21}\)

\(x=\dfrac{5}{21}:\dfrac{6}{7}=\dfrac{5}{18}\)

\(c.x:\dfrac{4}{3}=\dfrac{8}{9}\)

\(x=\dfrac{8}{9}\times\dfrac{4}{3}=\dfrac{32}{27}\)

a: \(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35-12}{20}=\dfrac{23}{20}\)

d: \(\left(-\dfrac{1}{4}\right)^2\cdot\dfrac{4}{11}+\dfrac{7}{11}\cdot\left(-\dfrac{1}{4}\right)^2=\dfrac{1}{16}\)

\(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35}{20}+\dfrac{-12}{20}=\dfrac{23}{20}\)

Bạn nên viết đề bằng công thức toán và ghi đầy đủ yêu cầu đề để mọi người hiểu đề của bạn hơn nhé.

a. \(\dfrac{3}{4}\) + \(\dfrac{-4}{5}\) - \(\dfrac{1}{2}\) = \(\dfrac{-1}{20}\)  - \(\dfrac{1}{2}\) = \(\dfrac{-11}{20}\) 

b. (4 - \(\dfrac{5}{12}\) ): 2 + \(\dfrac{5}{24}\) 

= \(\dfrac{43}{12}\) : 2 + \(\dfrac{5}{24}\) 

= \(\dfrac{43}{24}\) + \(\dfrac{5}{24}\) 

=\(\dfrac{48}{24}\) = 2

2.2 

\(\dfrac{4}{7}\) .x - \(\dfrac{2}{3}\) = \(\dfrac{1}{5}\) 

  \(\dfrac{4}{7}\) x   = \(\dfrac{1}{5}\) + \(\dfrac{2}{3}\) 

  \(\dfrac{4}{7}\) . x = \(\dfrac{13}{15}\) 

        x = \(\dfrac{91}{60}\)

2.1

\(a)\dfrac{3}{4}+\dfrac{-4}{5}-\dfrac{1}{2}\\ =\dfrac{3\times5}{4\times5}+\dfrac{-4\times4}{5\times4}-\dfrac{1\times10}{2\times10}\\ =\dfrac{15}{20}+\dfrac{-16}{20}-\dfrac{10}{20}\\ =\dfrac{15-16-10}{20}\\ =\dfrac{-11}{20}\)

\(b)\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}\\ =\left(\dfrac{4\times12}{1\times12}-\dfrac{5}{12}\right):2+\dfrac{5}{24}\\ =\left(\dfrac{48}{12}-\dfrac{5}{12}\right):2+\dfrac{5}{24}\\ =\left(\dfrac{48-5}{12}\right):2+\dfrac{5}{24}\\ =\dfrac{43}{12}:2+\dfrac{5}{24}\\ =\dfrac{43}{12}\times\dfrac{1}{2}+\dfrac{5}{24}\\ =\dfrac{43}{24}+\dfrac{5}{24}\\ =\dfrac{43+5}{24}\\ =\dfrac{48}{24}\\ =2\)

\(2.2\\ \dfrac{4}{7}\times x-\dfrac{2}{3}=\dfrac{1}{5}\\ \dfrac{4}{7}\times x=\dfrac{1}{5}+\dfrac{2}{3}\\ \dfrac{4}{7}\times x=\dfrac{1\times3}{5\times3}+\dfrac{2\times5}{3\times5}\\ \dfrac{4}{7}\times x=\dfrac{3}{15}+\dfrac{10}{15}\\ \dfrac{4}{7}\times x=\dfrac{13}{15}\\ x=\dfrac{13}{15}:\dfrac{4}{7}\\ x=\dfrac{13}{15}\times\dfrac{7}{4}\\ x=\dfrac{91}{60}\)