\(\left(\frac{1}{7}-\frac{1}{3}\right)x=\frac{28}{3}\left(\frac{1}{4}-\frac{1}{7}\right)\)

\(\left(-\frac{4}{21}\right)x=\frac{28}{3}.\frac{3}{28}\)

\(\frac{-4}{21}x=1\)

\(x=1:\frac{-4}{21}\)

\(x=-\frac{21}{4}\)

Vậy \(x=\frac{-21}{4}\)

= 51/20

----------------------------------

= 3/14

------------------------------------

= 4/7 - 2/7 

= 2/7

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= 17/45

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= 2/3 

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= 2 x 1/4 

= 1/2

a) \(\frac{3}{4}\)+ \(\frac{4}{3}\):\(\frac{2}{7}\)- \(\frac{4}{3}\)

=\(\frac{3}{4}\) +\(\frac{4}{3}\) .\(\frac{7}{2}\) -\(\frac{4}{3}\)

=\(\frac{3}{4}\) + \(\frac{14}{3}\) -\(\frac{4}{3}\)

=\(\frac{9}{12}\) +\(\frac{56}{12}\)

=\(\frac{56}{12}\) - \(\frac{4}{3}\)

=\(\frac{56}{12}\)- \(\frac{16}{12}\)

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

b) \(\frac{5}{2}\) - [\(\frac{1}{2}\) + (\(\frac{-2}{3}\)) .\(\frac{6}{5}\)].\(\frac{2}{5}\)

= \(\frac{5}{2}\) - [\(\frac{1}{2}\) + (\(\frac{-4}{5}\))].\(\frac{2}{5}\)

= \(\frac{5}{2}\) - (\(\frac{5}{10}\) +\(\frac{-8}{10}\)).\(\frac{2}{5}\)

=\(\frac{5}{2}\)-\(\frac{3}{10}\).\(\frac{2}{5}\)

=\(\frac{5}{2}\)-\(\frac{3}{25}\)

= \(\frac{125}{50}\)-\(\frac{6}{50}\)

= \(\frac{119}{50}\)

(Mình không chắc chắn lắm!^^)

A)  7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11

=7/38.(9/11+4/11-2/11)

=7/38

B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20

=5/31.(21/25-7/10-9/20)

=5/31.(-31/100)

=-1/20

Bài làm:

Ta có: \(\left(\frac{1}{2}x+\frac{3}{4}\right)^2\div\left(-\frac{3}{14}\right)=-\frac{7}{24}\)

\(\Leftrightarrow\left(\frac{1}{2}x+\frac{3}{4}\right)^2=\frac{1}{16}=\left(\frac{1}{4}\right)^2\)

\(\Leftrightarrow\orbr{\begin{cases}\frac{1}{2}x+\frac{3}{4}=\frac{1}{4}\\\frac{1}{2}x+\frac{3}{4}=-\frac{1}{4}\end{cases}}\Leftrightarrow\orbr{\begin{cases}\frac{1}{2}x=-\frac{1}{2}\\\frac{1}{2}x=-1\end{cases}}\Rightarrow\orbr{\begin{cases}x=-1\\x=-2\end{cases}}\)

(\(\frac{1}{2}\).x+\(\frac{3}{4}\))²: \(\frac{-3}{14}\)=\(\frac{-7}{24}\)
  (\(\frac{1}{2}\).x+\(\frac{3}{4}\))² =\(\frac{1}{16}\)
   (\(\frac{1}{2}\).x+\(\frac{3}{4}\))²=(\(\frac{1}{4}\))²
\(\hept{\begin{cases}\frac{1}{2}.x+\frac{3}{4}=\frac{1}{4}\\\frac{1}{2}.x+\frac{3}{4}=\frac{-1}{4}\end{cases}}\)<=>\(\hept{\begin{cases}\frac{1}{2}.x=\frac{1}{4}-\frac{3}{4}\\\frac{1}{2}.x=\frac{-1}{4}-\frac{3}{4}\end{cases}}\)<=>\(\hept{\begin{cases}\frac{1}{2}.x=-\frac{1}{2}\\\frac{1}{2}.x=-1\end{cases}}\)
<=>\(\hept{\begin{cases}x=\frac{-1}{2}:\frac{1}{2}=-1\\x=-1:\frac{1}{2}=-2\end{cases}}\)

`#040911`

`a)`

`3 1/3 x + 16 3/4 = -13,25`

`=> 3 1/3 x = -13,25 - 16 3/4`

`=> 3 1/3 x = -30`

`=> x = -30 \div 3 1/3`

`=> x =-9`

Vậy, `x = -9`

`b)`

`3 2/7*x - 1/8 = 2 3/4`

`=> 3 2/7x = 2 3/4 + 1/8`

`=> 3 2/7x = 23/8`

`=> x = 23/8 \div 3 2/7`

`=> x = 7/8`

Vậy, `x = 7/8`

`c)`

`x \div 4 1/3 = -2,5`

`=> x = -2,5 * 4 1/3`

`=> x = -65/6`

Vậy, `x = -65/6`

`d)`

`( (3x)/7 + 1) \div (-4) = (-1)/28`

`=> (3x)/7 +1 = (-1)/28 * (-4)`

`=> (3x)/7 + 1 = 1/7`

`=> (3x)/7 = 1/7 - 1`

`=> (3x)/7 = -6/7`

`=> 3x = -6`

`=> x = -6 \div 3`

`=> x = -2`

Vậy, `x = -2.`

a

=>10/3 . x + 16 + 3/4 = -13,25

=>10/3 x + 3/4 = -29,25

=>10/3 x = -30

=>x=-30 : 10/3

=>x=-30 . 3/10

=>x=-9

b.

=>23/7 x - 1/8 = = 11/4

=>23/7 x = 11/4 + 1/8

=>23/7 x= 22/8 + 1/8

=>23/7 x= 23/8

=>x=23/8 : 23/7

=>x=23/8 . 7/23

=>x=7/8

c.

=>x : 13/3 =-5/2

=>x=-5/2 . 13/3

=>x=-65/6

d.

=>3x/7 +1 = (-1/28) . (-4)

=>3x/7 + 1 = 1/7

=>3x/7 = -6/7

=>3x=-6

=>x=-2

a) \(3\dfrac{1}{3}x+16\dfrac{3}{4}=-13,25\)

\(\Rightarrow\dfrac{10}{3}x+\dfrac{67}{4}=-\dfrac{53}{4}\)

\(\Rightarrow\dfrac{10}{3}x=-30\)

\(\Rightarrow x=-30:\dfrac{10}{3}\)

\(\Rightarrow x=-9\)

b) \(3\dfrac{2}{7}x-\dfrac{1}{8}=2\dfrac{3}{4}\)

\(\Rightarrow\dfrac{23}{7}x-\dfrac{1}{8}=\dfrac{11}{4}\)

\(\Rightarrow\dfrac{23}{7}x=\dfrac{11}{4}+\dfrac{1}{8}\)

\(\Rightarrow\dfrac{23}{7}x=\dfrac{23}{8}\)

\(\Rightarrow x=\dfrac{23}{8}:\dfrac{23}{7}\)

\(\Rightarrow x=\dfrac{7}{8}\)

c) \(x:4\dfrac{1}{3}=-2,5\)

\(\Rightarrow x:\dfrac{13}{3}=-\dfrac{5}{2}\)

\(\Rightarrow x=-\dfrac{5}{2}\cdot\dfrac{13}{3}\)

\(\Rightarrow x=-\dfrac{65}{6}\)

d) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)

\(\Rightarrow\dfrac{3x}{7}+1=\dfrac{-1}{28}\cdot-4\)

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

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

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

\(\Rightarrow x=-2\)

7/5+4/5   7/20-1/4         5/4x3/9      7/2 : 8

=7+4/5    =7/20-5/20      =5/4x1/3    =7/2x 1/8

=11/5       =7-5/20          =5/12         =7/16

                 = 1/10 

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