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a.\(x+\dfrac{4}{7}=\dfrac{38}{21}\)

\(x=\dfrac{38}{21}-\dfrac{4}{7}\)

\(x=\dfrac{38}{21}-\dfrac{12}{21}=\dfrac{26}{21}\)

b.\(x-\dfrac{1}{3}=\dfrac{7}{45}:\dfrac{2}{15}\)

\(x-\dfrac{1}{3}=\dfrac{7}{6}\)

\(x=\dfrac{7}{6}+\dfrac{1}{3}\)

\(x=\dfrac{7}{6}+\dfrac{2}{6}=\dfrac{9}{6}\)

15 tháng 4 2022

x = 38/21 - 4/7

x = 26/21

 

x - 1/3 = 7/6

x = 7/6 + 1/3

x = 3/2

7 tháng 5 2022

7 tháng 5 2022

\(a.x+\dfrac{3}{7}=\dfrac{2}{5}:\dfrac{18}{35}\\x+\dfrac{3}{7}=\dfrac{2}{5}\times\dfrac{35}{18} \\ x+\dfrac{3}{7}=\dfrac{7}{9}\\ x=\dfrac{7}{9}-\dfrac{3}{7}\\ x=\dfrac{22}{63}\)

\(b.x\times\dfrac{5}{9}=\dfrac{4}{5}-\dfrac{1}{3}\\x\times\dfrac{5}{9}=\dfrac{7}{15}\\ x=\dfrac{7}{15}:\dfrac{5}{9}\\ x= \dfrac{21}{25}\)

7 tháng 5 2022

a. x + \(\dfrac{3}{7}\)\(\dfrac{2}{5}:\dfrac{18}{25}=>x+\dfrac{3}{7}=\dfrac{2}{5}\)x\(\dfrac{35}{18}=>x+\dfrac{3}{7}=\dfrac{7}{9}\)

=> x = \(\dfrac{7}{9}-\dfrac{3}{7}=\dfrac{49}{63}-\dfrac{27}{63}=\dfrac{22}{63}\)

b. \(x\) x \(\dfrac{5}{9}\)\(\dfrac{4}{5}-\dfrac{1}{3}\)

=> \(x\) x \(\dfrac{5}{9}\)\(\dfrac{12}{15}-\dfrac{5}{15}=>x\) x \(\dfrac{5}{9}\)\(\dfrac{7}{15}\)

=> x = \(\dfrac{7}{15}:\dfrac{5}{9}\)

=> x = \(\dfrac{21}{25}\)

7 tháng 5 2022

a,x + 3/7 = 2/5 : 18/35

   x + 3/7 = 7/9

   x          = 7/9 - 3/7

   x          = 22/63

vậy x = ...

b, X x 5/9 = 4/5 - 1/3

    X x 5/9 = 7/15

            X  = 7/15 : 5/9

            X  = 21/25

vậy X = ...

 

3 tháng 5 2023

\(a,\left(\dfrac{31}{35}-\dfrac{4}{7}\right)\times\dfrac{8}{7}:2\\ =\left(\dfrac{31}{35}-\dfrac{4\times5}{35}\right)\times\dfrac{8}{7}:2\\ =\dfrac{11}{35}\times\dfrac{8}{7}:2\\ =\dfrac{88}{245}:2\\ =\dfrac{44}{245}\\ b,\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)\\ =\left(\dfrac{2-1}{2}\right)\times\left(\dfrac{3-1}{3}\right)\times\left(\dfrac{4-1}{4}\right)\times\left(\dfrac{5-1}{5}\right)\\ =\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\\ =\dfrac{1}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\\ =\dfrac{1}{4}\times\dfrac{4}{5}=\dfrac{1}{5}\)

3 tháng 5 2023

a, ( \(\dfrac{31}{35}\) - \(\dfrac{4}{7}\)\(\times\) \(\dfrac{8}{7}\): 2

\(\left(\dfrac{31}{35}-\dfrac{20}{35}\right)\) \(\times\) \(\dfrac{8}{7}\) : 2

\(\dfrac{11}{35}\) \(\times\) \(\dfrac{8}{7}\) \(\times\) \(\dfrac{1}{2}\)

\(\dfrac{44}{35}\) \(\times\) \(\dfrac{4}{7}\)

\(\dfrac{44}{245}\)

b, ( 1 - \(\dfrac{1}{2}\)\(\times\) ( 1 - \(\dfrac{1}{3}\)\(\times\) ( 1 - \(\dfrac{1}{4}\)\(\times\) ( 1 - \(\dfrac{1}{5}\))

\(\dfrac{1}{2}\) \(\times\) \(\dfrac{2}{3}\) \(\times\) \(\dfrac{3}{4}\) \(\times\) \(\dfrac{4}{5}\)

\(\dfrac{1}{5}\) \(\times\) \(\dfrac{2\times3\times4}{2\times3\times4}\)

\(\dfrac{1}{5}\)

21 tháng 4 2022

a) 2 + 1/3 - x = 1 + 1/4

7/3 -x = 5/4

x = 7/3 - 5/4

x = 13/12


b) (2/7 x 2) : x = 1 :7/2 

4/7 : x = 2/7

x = 4/7 : 2/7

x = 2

21 tháng 4 2022

a) 2 + 1/3 - x = 1 + 1/4

           7/3 -x = 5/4

                  x = 7/3 - 5/4

                  x = 13/12


b) (2/7 x 2) : x = 1 :7/2 

          4/7 : x = 2/7

                  x = 4/7 : 2/7

                  x = 2

19 tháng 3 2022

đề bài sai sao ý 9/15 mà nếu 9/ 16 thì ko tính thận tiện đc

\(\dfrac{10}{15}\)x\(\dfrac{9}{16}+\dfrac{7}{15}\)x\(\dfrac{10}{15}\)

=> \(\dfrac{10}{15}\)x\(\left(\dfrac{9}{16}+\dfrac{7}{15}\right)\)

=> \(\dfrac{10}{15}\)x\(\dfrac{247}{240}\)

=> \(\dfrac{247}{360}\)

17 tháng 3 2022

a) 3 x 1/5 + 2/5 = 3/5 + 2/5 = 1

b) 3 : 1/5 - 2/5 = 15 - 2/5 = 73/5

bài 2 :
a) X x 1/2 = 1 - 1/5

    X x 1/2 = 4/5 

           X   = 4/5 : 1/2

           X   = 8/5 

vậy x =...

b) x : 1/3 = 1 + 1/5

    x : 1/3 = 6/5

          x   = 6/5 x 1/3

          x   = 2/5

vậy x =...

14 tháng 8 2023

a) x + \(\dfrac{3}{4}\) = \(\dfrac{5}{3}\)

    x = \(\dfrac{5}{3}\) - \(\dfrac{3}{4}\)

    x = \(\dfrac{20}{12}\) - \(\dfrac{9}{12}\)  

    x =  \(\dfrac{11}{12}\) 

b) x - \(\dfrac{2}{3}\) = \(\dfrac{7}{2}\)

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

    x = \(\dfrac{21}{6}\) + \(\dfrac{4}{6}\) 

    x = \(\dfrac{25}{6}\)

14 tháng 8 2023

nhanh lên nhé 

11 tháng 5 2023

\(a,x-\dfrac{5}{7}=\dfrac{3}{5}\times\dfrac{1}{2}\)

\(x-\dfrac{5}{7}=\dfrac{3}{10}\)

\(x=\dfrac{3}{10}+\dfrac{5}{7}\)

\(x=\dfrac{21}{70}+\dfrac{50}{70}\)

\(x=\dfrac{71}{70}\)

\(Vayx=\dfrac{71}{70}\)

\(b,x\times\dfrac{2}{3}=\dfrac{5}{8}+\dfrac{3}{4}\)

\(x\times\dfrac{2}{3}=\dfrac{5}{8}+\dfrac{6}{8}\)

\(x\times\dfrac{2}{3}=\dfrac{11}{8}\)

\(x=\dfrac{11}{8}:\dfrac{2}{3}\)

\(x=\dfrac{11}{8}\times\dfrac{3}{2}\)

\(x=\dfrac{33}{16}\)

\(Vayx=\dfrac{33}{16}\)