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13 tháng 10 2017

2 - x = \(\frac{1}{5}\)\(\frac{1}{4}\)                                          

2 -x = \(\frac{4}{5}\)

    x = 2 - \(\frac{4}{5}\)

   x = \(\frac{6}{5}\)

3 - x \(\times\) \(\frac{1}{3}\)\(\frac{1}{6}\) \(\Rightarrow\) 3 - x = \(\frac{1}{6}\) \(\div\frac{1}{3}\)

                                                 3 - x = \(\frac{1}{2}\) \(\Rightarrow\) x = 3 - \(\frac{1}{2}\) \(\Rightarrow\) x = \(\frac{5}{2}\)

12 tháng 10 2017

2 - x = 1/5 : 1/4

2 - x = 1/5 * 4

2 - x = 4/5

x = 2 - 4/5

x = 6/5

3 - x = 1/3 : 1/6

3 - x = 1/3 * 6

3 - x = 2

x = 3 - 2

x = 1

b) 1/3 * 1/2 + 1/5 * 1/2

= 1/2 * (1/3 + 1/5)

= 1/2 * 8/15

= 4/15

373737/414141 : 4545/4141

= 37/41 : 45/41

= 37/41 * 41/45

= 37/45

2727/4242 + 13/42 + 444444/424242

= 9/14 + 13/42 + 22/21

= 2

2 tháng 7 2017

\(\frac{1}{x}:\frac{1}{3}\times\frac{1}{4}=\frac{5}{6}\)

\(\frac{3}{x}\times\frac{1}{4}=\frac{5}{6}\)

\(\frac{3}{x}=\frac{5}{6}:\frac{1}{4}\)

\(\frac{3}{x}=\frac{10}{3}\)

\(\Leftrightarrow3.3=10.x\)

\(\Leftrightarrow9=10.x\)

\(\Leftrightarrow x=\frac{9}{10}\)

2 tháng 7 2017

\(\frac{1}{x}:\frac{1}{3}\times\frac{1}{4}=\frac{5}{6}\)

\(\frac{1}{x}:\frac{1}{3}=\frac{10}{3}\)

\(\frac{3}{x}=\frac{10}{3}\)

\(x=3.\frac{3}{10}=\frac{9}{10}\)

21 tháng 9 2020

                                                            Bài giải

\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)

\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{394}{90}\)

\(\frac{15}{17}-\frac{11}{13}+\frac{3}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)

\(\frac{9}{12}\text{ x }\frac{4}{3}\text{ : }\frac{8}{5}=\frac{9}{12}\text{ x }\frac{4}{3}\text{ x }\frac{5}{8}=\frac{9\text{ x }4\text{ x }5}{12\text{ x }3\text{ x }8}=\frac{5}{8}\)

\(\frac{4}{5}\text{ x }\frac{15}{8}\text{ : }\frac{5}{7}=\frac{4}{5}\text{ x }\frac{15}{8}\text{ x }\frac{7}{5}=\frac{4\text{ x }15\text{ x }7}{5\text{ x }8\text{ x }5}=\frac{21}{10}\)

26 tháng 4 2021

\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\) 

\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{197}{45}\)

\(\frac{15}{17}-\frac{11}{13}+\frac{1}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)

\(\frac{9}{12}\times\frac{4}{3}:\frac{8}{5}=1:\frac{8}{5}=\frac{5}{8}\)

\(\frac{4}{5}\times\frac{15}{8}:\frac{5}{7}=\frac{3}{2}:\frac{5}{7}=\frac{21}{10}\)

22 tháng 10 2018

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

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

                     \(x\times2=\frac{4}{5}\)

                             \(x=\frac{4}{5}\div2\)

                            \(x=\frac{4}{10}\)

16 tháng 9 2017

\(\frac{1010+1111+1212+1313+1414+1515+1616+1717}{2020+2121+2222+2323+2424+2525+2626+2727}\)

\(=\frac{101.10+101.11+...+101.17}{101.20+101.21+...+101.27}\)

\(=\frac{101.\left(10+11+...+17\right)}{101.\left(20+21+...+27\right)}\)

\(=\frac{108}{188}\)

\(=\frac{27}{47}\)

16 tháng 9 2017

\(2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{4}{96}\right)\cdot5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{1}{24}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{20}{120}+\frac{16}{120}+\frac{9}{120}+\frac{5}{120}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{5}{12}:5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{1}{12}.y>\frac{5}{6}\)

Đặt :\(\frac{1}{12}.y=2\Rightarrow y=2:\frac{1}{12}=24\)

\(\frac{1}{12}.y=\frac{5}{6}\Rightarrow y=\frac{5}{6}:\frac{1}{12}=10\)

\(\Rightarrow24>y>10\)

\(\Rightarrow y\in\left\{11;12;...;23\right\}\)

20 tháng 10 2019

a) \(x+4\frac{1}{5}=5\frac{2}{3}\times10\frac{1}{2}\)
    \(x+\frac{21}{5}=\frac{17}{3}\times\frac{21}{2}\)
    \(x+\frac{21}{5}=\frac{119}{2}\)
                   \(x=\frac{119}{2}-\frac{21}{5}\)
                   \(x=\frac{553}{10}\)
b) \(\frac{24}{5}-x=2\frac{1}{4}:1\frac{3}{4}\)
    \(\frac{24}{5}-x=\frac{9}{4}:\frac{7}{4}\)
    \(\frac{24}{5}-x=\frac{9}{4}.\frac{4}{7}\)
    \(\frac{24}{5}-x=\frac{9}{7}\)
                  \(x=\frac{24}{5}-\frac{9}{7}\)
                  \(x=\frac{123}{35}\)
 

24 tháng 9 2020

a,=25/6;7/6=25/6x6/7=25/7

b,=7/2x32/6=56/3

c,=17/5-11/10=34/10-11/10=23/10

d,=8/3+11/4=32/12+33/12=65/12