A) 5/4 x X = 3/8 + 5/12

5/4 x X = 19/24

        X  = 19/24 : 5/4

        X  = 19/30

vậy x =...

B, 3 x 7/10 + 7/10 x 5 + 2 x 7/10

  = 7/10 x ( 3 + 5 + 2)

  = 7/10 x 10

  = 7

Giúp tớ với mọi người ơi

x= \(\frac{5}{3}-\frac{3}{7}=\frac{26}{21}\)

x=\(\frac{3}{10}+\frac{4}{5}=\frac{11}{10}\)

x=\(\frac{4}{3}-\frac{4}{5}=\frac{8}{15}\)

x=\(\frac{7}{8}:\frac{5}{6}=\frac{7}{8}x\frac{6}{5}=\frac{42}{40}=\frac{21}{10}\)

x=\(\frac{3}{2}x\frac{9}{7}=\frac{27}{14}\)

x=\(\frac{14}{15}:\frac{3}{4}=\frac{14}{15}x\frac{4}{3}=\frac{56}{45}\)

Chúc bạn học tốt!

\(\left(\frac{6}{11}+\frac{5}{11}\right)x\frac{3}{7}=\frac{11}{11}x\frac{3}{7}\)

                                 \(=1x\frac{3}{7}\) 

                                  \(=\frac{3}{7}\) 

\(\frac{3}{5}x\frac{7}{9}+\frac{3}{5}x\frac{2}{9}=\frac{3}{5}x\left(\frac{7}{9}+\frac{2}{9}\right)\)

                                \(=\frac{3}{5}x\frac{9}{9}\) 

                                 \(=\frac{3}{5}x1\) 

                                  \(=\frac{3}{5}\) 

\(\left(\frac{6}{7}-\frac{4}{7}\right):\frac{2}{5}=\frac{2}{7}:\frac{2}{5}\)

                             \(=\frac{2}{7}x\frac{2}{5}\) 

                              \(=\frac{4}{35}\) 

\(\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}=\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}\)

                                    \(=\frac{15}{15}:\frac{2}{11}\) 

                                     \(=1:\frac{2}{11}\) 

                                       \(=1x\frac{11}{2}\) 

                                         \(=\frac{11}{2}\)

minh nam tinh bang hai cach nhe ban

a)\(x+\frac{15}{16}+\frac{7}{8}=\frac{15}{4}\)

\(x+\frac{29}{16}=\frac{15}{4}\)

\(x=\frac{15}{4}-\frac{29}{16}\)

\(x=\frac{31}{16}\)

b)\(x-\frac{27}{28}-\frac{9}{14}=\frac{13}{7}\)

\(x-\frac{45}{28}=\frac{13}{7}\)

\(x=\frac{13}{7}+\frac{45}{28}\)

\(x=\frac{97}{28}\)

c)\(x\times\frac{1}{5}+x+\frac{1}{6}=\frac{2}{3}\)

\(x\times\frac{1}{5}+x=\frac{2}{3}-\frac{1}{6}\)

\(x\times\left(\frac{1}{5}+1\right)=\frac{1}{2}\)

\(x\times\frac{6}{5}=\frac{1}{2}\)

\(x=\frac{1}{2}:\frac{6}{5}\)

\(x=\frac{5}{12}\)

d)\(x:14=\frac{1}{4}+\frac{2}{9}+\frac{3}{4}\)

\(x:14=\frac{11}{9}\)

\(x=\frac{11}{9}\times14\)

\(x=\frac{154}{9}\)

#H

a) X x 5/8 = 1/3
    X          = 1/3 : 5/8
    X          = 1/3 x 8/5
    X           =    8/15

b) 12/11 x X = 4
                 X = 4 : 12/11
                 X = 4 x 11/12
                 X =   33

c) 5 x X = 7/9
          X = 7/9 : 5
          X = 7/9 x 5
          X = 35/45
          X = 7/9
Nếu mình có trả lời sai thì thông cảm cho mình vì mình cũng lớp 4 :)  

các bạn trả lới cho đàng hoàng tính mình hơi nóng

a) x + 2/5 = 1/2

x = 1/10

b) 2/3 - x = 8/17

x = 10/51

c) x * 6/7 = 5/14

x = 5/12

d) x : 2/3 = 4/9

x = 8/27

...

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'''''

...

\(a.\dfrac{3\times4\times7}{12\times8\times9}=\dfrac{3\times4\times7}{3\times4\times4\times2\times9}\\ =\dfrac{7}{4\times2\times9}=\dfrac{7}{72}\\ b.\dfrac{4\times5\times6}{12\times10\times8}=\dfrac{4\times5\times2\times3}{4\times3\times5\times2\times4\times2}=\dfrac{1}{8}\\ c.\dfrac{5\times6\times7}{12\times14\times15}=\dfrac{5\times6\times7}{2\times6\times7\times2\times5\times3}\\ =\dfrac{1}{2\times2\times3}=\dfrac{1}{12}\)

tra loi nhanh ho mk voi

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\)

    = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\)

      = \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\)

      = \(1-\frac{1}{7}\)

      =   \(\frac{7}{7}-\frac{1}{7}\)

        = \(\frac{6}{7}\)

2) \(\frac{7}{4}-x.\frac{4}{3}=\frac{5}{19}\)

              \(x.\frac{4}{3}=\frac{7}{4}-\frac{5}{19}\)

         \(x.\frac{4}{3}=\frac{133}{76}-\frac{20}{76}\)

\(x.\frac{4}{3}=\frac{113}{76}\)

      \(x=\frac{113}{76}:\frac{4}{3}\)

      \(x=\frac{399}{304}\)

VẬY \(x=\frac{399}{304}\)

b) \(\left(x+\frac{3}{4}\right).\frac{5}{7}=\frac{10}{9}\)

      \(\left(x+\frac{3}{4}\right)=\frac{10}{9}:\frac{5}{7}\)

     \(x+\frac{3}{4}=\frac{14}{9}\)

              \(x=\frac{14}{9}-\frac{3}{4}\)

               \(x=\frac{29}{36}\)

Vậy \(x=\frac{29}{36}\)

c) \(x.\frac{1}{2}+\frac{3}{2}.x=\frac{4}{5}\)

\(x.\left(\frac{1}{2}+\frac{3}{2}\right)=\frac{4}{5}\)

\(x.2=\frac{4}{5}\)

     \(x=\frac{4}{5}:2\)

      \(x=\frac{2}{5}\)

Vậy \(x=\frac{2}{5}\)

Chúc bạn học tốt !!!