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1/2x - 2/3x = 7/12
(1/2 - 2/3)x = 7/12
1/10x = 7/12
x = 7/12 : 1/10
x = 35/6
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.x+\dfrac{1}{6}=-\dfrac{3}{8}\)
\(\Leftrightarrow x=-\dfrac{13}{24}\)
\(b.2-\left(\dfrac{3}{4}-x\right)=\dfrac{7}{12}\)
\(\Leftrightarrow2-\dfrac{3}{4}+x=\dfrac{7}{12}\)
\(\Leftrightarrow x=-\dfrac{2}{3}\)
\(c.\dfrac{1}{2}x+\dfrac{1}{8}x=\dfrac{3}{4}\)
\(\Leftrightarrow\dfrac{5}{8}x=\dfrac{3}{4}\)
\(\Leftrightarrow x=\dfrac{6}{5}\)
\(d.75\%-1\dfrac{1}{2}+0,5:\dfrac{5}{12}-\left(\dfrac{-1}{2}\right)^2\)
\(=\dfrac{75}{100}-\dfrac{3}{2}+\dfrac{1}{2}:\dfrac{5}{12}-\dfrac{1}{4}\)
\(=-\dfrac{3}{4}+\dfrac{6}{5}-\dfrac{1}{4}\)
\(=\dfrac{1}{5}\)
a) \(x+\dfrac{1}{6}=\dfrac{-3}{8}\)
\(x=\dfrac{-3}{8}-\dfrac{1}{6}\)
\(x=\dfrac{-13}{24}\)
vậy x =....
b) \(2-\left(\dfrac{3}{4}-x\right)=\dfrac{7}{12}\)
\(\dfrac{3}{4}-x=2-\dfrac{7}{12}\)
\(\dfrac{3}{4}-x=\dfrac{17}{12}\)
\(x=\dfrac{3}{4}-\dfrac{17}{12}\)
\(x=\dfrac{-2}{3}\)
vậy x =....
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 0,5 x - \(\frac{2}{3}\)x = \(\frac{7}{12}\)
x . ( 0,5 - \(\frac{2}{3}\)) = \(\frac{7}{12}\)
x . \(\frac{-1}{6}\) = \(\frac{7}{12}\)
x = \(\frac{7}{12}\): \(\frac{-1}{6}\)
x = \(\frac{-7}{2}\)
b) x : \(\frac{25}{3}\) = -25
x = -25 . \(\frac{25}{3}\)
x = \(\frac{-625}{3}\)
c) 5,5 x = \(\frac{13}{15}\)
x = \(\frac{13}{15}\): 5,5
x = \(\frac{26}{165}\)
d) (\(\frac{3x}{7}\)+ 1 ) : ( -4) = \(\frac{-1}{28}\)
( \(\frac{3x}{7}\)+ 1 ) = \(\frac{-1}{28}\). ( -4)
\(\frac{3x}{7}\)+ 1 = \(\frac{1}{7}\)
\(\frac{3x}{7}\) = \(\frac{1}{7}\)- 1
\(\frac{3x}{7}\) = \(\frac{-6}{7}\)
=> x = -2
e) y + 30% y = -1,3
y + \(\frac{3}{10}\)y = -1,3
y . ( 1 + \(\frac{3}{10}\)) = -1,3
y . \(\frac{13}{10}\) = -1,3
y = -1,3 : \(\frac{13}{10}\)
y = -1
g) y - 25% y = \(\frac{1}{2}\)
y - \(\frac{1}{4}\)y = \(\frac{1}{2}\)
y . ( 1 - \(\frac{1}{4}\)) = \(\frac{1}{2}\)
y . \(\frac{3}{4}\) = \(\frac{1}{2}\)
y = \(\frac{1}{2}\): \(\frac{3}{4}\)
y = \(\frac{2}{3}\)
ai tốt bụng thì tk cho mk nha, mk đg âm điểm đây huhu
![](https://rs.olm.vn/images/avt/0.png?1311)
a, (0.5-\(\dfrac{2}{3}\))x=\(\dfrac{7}{12}\)
\(\Leftrightarrow\)\(\dfrac{-1}{6}\)x=\(\dfrac{7}{12}\)
\(\Leftrightarrow\)x= \(\dfrac{-7}{2}\)=-3,5
b.x \(\div\)4\(\dfrac{1}{3}\)=-2,5
\(\Leftrightarrow\) x \(\div\)\(\dfrac{13}{3}\)=-2,5
\(\Leftrightarrow\) x = -2,5 \(\times\)\(\dfrac{13}{3}\)
\(\Leftrightarrow\) x = \(\dfrac{-65}{6}\)
x.(0.5-\(\dfrac{2}{3}\))=\(\dfrac{7}{12}\)
x=\(\dfrac{-7}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1)a, \(0,5x-\frac{2}{3}x=\frac{7}{12}\) b) \(x:4\frac{1}{3}=-\frac{2}{5}\)
\(x\left(0,5-\frac{2}{3}\right)=\frac{7}{12}\) \(x=-\frac{2}{5}.4\frac{1}{3}\)
\(-\frac{1}{6}x=\frac{7}{12}\) \(x=-\frac{26}{15}\)
\(x=\frac{-7}{2}\)
c) \(\left(\frac{3x}{7}+1\right):\left(-4\right)=-\frac{1}{28}\) d) \(x+30\%x=-1,3\)
\(\frac{3x}{7}+1=-\frac{1}{28}.\left(-4\right)\) \(x\left(1+30\%\right)=-1,3\)
\(\frac{3x}{7}+1=\frac{1}{7}\) \(1,3x=-1,3\)
\(\frac{3x}{7}=-\frac{6}{7}\) \(x=-1,3:1,3\)
\(x=-6.7:7:3\) \(x=-1\)
\(x=-2\)
Bài 2:
\(\frac{3}{5.7}+\frac{3}{7.9}+...+\frac{3}{2019.2021}=\frac{3}{2}\left(\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{2019.2021}\right)\)
\(=\frac{3}{2}\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{2019}-\frac{1}{2021}\right)\)
\(=\frac{3}{2}.\left(\frac{1}{5}-\frac{1}{2021}\right)\)
\(=\frac{3}{2}.\frac{2016}{10105}\)
\(=\frac{3024}{10105}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow\frac{3}{2}x=0,5-\frac{12}{7}\)
\(\Leftrightarrow\frac{3}{2}x=-\frac{17}{14}\)
\(\Leftrightarrow x=-\frac{17}{14}:\frac{3}{2}\)
\(\Leftrightarrow x=-\frac{17}{21}\)