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![](https://rs.olm.vn/images/avt/0.png?1311)
0,5x-2/3x=7/12
=>(1/2-2/3).x=7/12
=>-1/6x=7/12
=>x=7/12:1/6
=>x=7/2
b, x:4 1/3=-2,5
=>x:13/3=-2,5
=>x=-5/2x13/3
=>x=-13
c,5,5x=13/15
=>11/2x=13/15
=>x=13/15:11/2
=>x=26/165
d,(3x/7+1):-4=-1/28
=>3x/7+1=-1/28x(-4)
=>3x/7+1=-1/7
=>3x/7=-1/7-1
=>3x/7=-8/7
=>3x=-8/7x7
=>3x=8
=>x=8:3
=>x=8/3
\(0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\left(\frac{1}{2}-\frac{2}{3}\right)x=\frac{7}{12}\)
\(\frac{-1}{6}x=\frac{7}{12}\)
\(x=-21\)
b,c,d tương tự
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 2 :
1) \(x-70=-45\) 2) \(\frac{4}{7}:x=\frac{12}{28}\)
\(\Rightarrow\) \(x=-45+70\) \(\Rightarrow x=\frac{4}{7}:\frac{12}{28}\)
\(\Rightarrow\) \(x=25\) \(\Rightarrow x=\frac{4}{3}\)
Vậy \(x=25\) Vậy \(x=\frac{4}{3}\)
3) Giống câu c) ở bài 1
4) \(x-50=-35\) 5) \(\frac{4}{7}.x=\frac{11}{18}\)
\(\Rightarrow x=-35+50\) \(\Rightarrow x=\frac{11}{28}:\frac{4}{7}\)
\(\Rightarrow x=15\) \(\Rightarrow x=\frac{77}{72}\)
Vậy \(x=15\) Vậy \(x=\frac{77}{72}\)
6) \(\left(\frac{2}{3}x+2,5\right):2\frac{2}{6}=6\)
\(\Rightarrow\)\(\left(\frac{2}{3}x+2,5\right):\frac{14}{6}=6\)
\(\Rightarrow\) \(\frac{2}{3}x+2,5=6.\frac{14}{6}\)
\(\Rightarrow\frac{2}{3}x+2,5=14\)
\(\Rightarrow\frac{2}{3}x=\frac{23}{2}\)
\(\Rightarrow x=\frac{23}{2}:\frac{2}{3}\)
\(\Rightarrow x=\frac{69}{4}\)
Vậy \(x=\frac{69}{4}\)
Bài 1:
1) \(\frac{7}{5}+\frac{-8}{5}=-\frac{1}{5}\)
2) \(-\frac{6}{5}.\frac{15}{24}=-\frac{3}{4}\)
3) \(\left(\frac{2}{3}+1,5\right)-3,5:7\frac{1}{2}=\)\(\frac{13}{6}-\frac{7}{15}=\frac{17}{10}\)
4) \(\frac{5}{8}-\frac{-7}{9}=\frac{5}{8}+\frac{7}{9}=\frac{101}{72}\)
5)\(\frac{-7}{3}.\frac{12}{28}=-1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(=\left(-\dfrac{25}{140}+\dfrac{245}{140}+\dfrac{32}{140}\right)\cdot\dfrac{-69}{20}\)
\(=\dfrac{252}{140}\cdot\dfrac{-69}{20}\)
\(=\dfrac{9}{5}\cdot\dfrac{-69}{20}=\dfrac{-621}{100}\)
b: \(=\left(6-2-\dfrac{4}{5}\right)\cdot\dfrac{25}{8}-\dfrac{8}{5}\cdot4\)
\(=\dfrac{16}{5}\cdot\dfrac{25}{8}-\dfrac{32}{5}=\dfrac{18}{5}\)
c: \(=\left(\dfrac{2}{24}+\dfrac{18}{24}+\dfrac{14}{24}\right):\dfrac{-17}{8}\)
\(=\dfrac{34}{24}\cdot\dfrac{-8}{17}=\dfrac{-1}{3}\cdot2=-\dfrac{2}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)x(1/2-2/3)=7/12
x.(-1/6)=7/12
x=7/12 / (-1/6)
x=-7/2
b)x=13/15 / 5,5
x=26/165
c)3x/7 + 1=-1/28.(-4)
3x/7 + 1=1/7
3x/7=1/7-1=-6/7
3x=-6/7.7=-6
x=-6:3=-2
![](https://rs.olm.vn/images/avt/0.png?1311)
a. \(0,5x-\frac{2}{3}x=\frac{7}{12}\)
=>\(\left(0,5-\frac{2}{3}\right).x=\frac{7}{12}\)
=>\(-\frac{1}{6}.x=\frac{7}{12}\)
=>\(x=\frac{7}{12}:-\frac{1}{6}=-\frac{7}{2}\)
_Hok tốt_
b.\(x:4\frac{1}{3}=-2,5\)
=>\(x:\frac{13}{3}=-2,5\)
=>\(x=-2,5.\frac{13}{3}=-\frac{65}{6}\)
_Hok tốt_
![](https://rs.olm.vn/images/avt/0.png?1311)
A)X.(0,5-2/3)=7/12
X.(-1/6)=7/12
X=7/12chia(-1/6)
X=11/3
B)X=-2,5.4/1/3=-26/15
C)X=13/15chia 5,5=26/165
D)X=[3x/7+1]=(-1)/28.(-4)
X=[3x/7+1]=1/112
X=1/112-1
X=-111/112
X=-111/112.3x/7
X=-333/784
a) \(0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(-\frac{1}{6}x=\frac{7}{12}\)
\(x=\frac{7}{12}:\left(-\frac{1}{6}\right)\)
\(x=-\frac{7}{2}\)
b) \(x:4\frac{1}{3}=-2,5\)
\(x=-2,5\)x \(4\frac{1}{3}\)
\(x=-\frac{65}{6}\)
c) \(5,5x=\frac{13}{15}\)
\(x=\frac{13}{15}:5,5\)
\(x=\frac{26}{165}\)
d)\(\left[\frac{3x}{7}+1\right]:\left(-4\right)=\frac{-1}{28}\)
\(\frac{3x}{7}+1=\left(\frac{-1}{28}\right)\)x\(\left(-4\right)\)
\(\frac{3x}{7}+1=\frac{1}{7}\)
\(3x:7=\frac{1}{7}-1\)
\(3x:7=-\frac{6}{7}\)
\(3x=\left(-\frac{6}{7}\right)\)x \(7\)
\(3x=-6\)
\(x=-2\)
a,5/10-2/3x=7/12 b, x:4 1/3=-2,5 c, 5,5x=13/15
2/3x=5/10-7/12 x:13/3=-25/10 55/10x=13/15
2/3x=30/60-35/60 x=-25/10.13/3 x=13/15:55/10
2/3x=-1/12 x=-65/6 x=13/15.10/55
x=-1/12:2/3 x=26/165
x=-1/12.3/2
x=-1/8
d,(3x/7+1):(-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=-6:3
x=-2
=>x=-2
ai giúp e ko ạ..huhu