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VN
15 tháng 8 2016
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
15 tháng 8 2016
\(0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\left(\frac{1}{2}-\frac{2}{3}\right)x=\frac{7}{12}\)
\(\frac{-1}{6}x=\frac{7}{12}\)
\(x=-21\)
b,c,d tương tự
11 tháng 7 2017
\(a.-8:\left(4\dfrac{1}{5}x+\dfrac{3}{10}\right)=4\dfrac{4}{9}\)
\(4\dfrac{1}{5}x+\dfrac{3}{10}=\left(-8\right):4\dfrac{4}{9}\)
\(4\dfrac{1}{5}x+\dfrac{3}{10}=\dfrac{-9}{5}\)
\(4\dfrac{1}{5}x=\dfrac{-9}{5}-\dfrac{3}{10}\)
\(4\dfrac{1}{5}x=\dfrac{-21}{10}\)
\(x=\dfrac{-21}{10}:\dfrac{21}{5}\)
\(x=\dfrac{-1}{2}\)
Vay \(x=\dfrac{-1}{2}\).
\(b.4\dfrac{2}{3}-\left(\dfrac{3}{5}:x\right)=-20\%\)
\(\dfrac{14}{3}-\left(\dfrac{3}{5}:x\right)=\dfrac{-1}{5}\)
\(\dfrac{3}{5}:x=\dfrac{14}{3}-\dfrac{-1}{5}\)
\(\dfrac{3}{5}:x=\dfrac{73}{15}\)
\(x=\dfrac{3}{5}:\dfrac{73}{15}\)
\(x=\dfrac{9}{73}\)
Vay \(x=\dfrac{9}{73}\).
Câu c; d; e tương tự nhé.
KN
1 tháng 4 2019
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_
KN
1 tháng 4 2019
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_
25 tháng 3 2018
\(\frac{x-2}{27}+\frac{x-3}{26}+\frac{x-4}{25}+\frac{x-5}{24}+\frac{x-44}{5}=1\)
\(\Leftrightarrow\left(\frac{x-2}{27}-1\right)+\left(\frac{x-3}{26}-1\right)+\left(\frac{x-4}{25}-1\right)+\left(\frac{x-5}{24}-1\right)\)\(+\left(\frac{x-44}{5}+3\right)=1-1\)
\(\Leftrightarrow\frac{x-29}{27}+\frac{x-29}{26}+\frac{x-29}{25}+\frac{x-29}{24}\)\(+\frac{x-29}{5}=0\)
\(\Leftrightarrow\left(x-29\right)\left(\frac{1}{27}+\frac{1}{26}+\frac{1}{25}+\frac{1}{24}+\frac{1}{5}\right)=0\)
Mà \(\frac{1}{27}+\frac{1}{26}+\frac{1}{25}+\frac{1}{24}+\frac{1}{5}\ne0\)
=> x - 29 = 0
=> x = 29.
ML
9 tháng 4 2017
\(\frac{1}{20}+\frac{1}{44}+\frac{1}{77}+...+\frac{2}{x\left(x+3\right)}=\frac{101}{770}\)
\(\Rightarrow\)\(\frac{3}{2}.\left(\frac{1}{20}+\frac{1}{44}+\frac{1}{77}+...+\frac{2}{x\left(x+3\right)}\right)=\frac{101}{770}\).
\(\Rightarrow\)\(\frac{3}{40}+\frac{3}{88}+\frac{3}{154}+...+\frac{3}{x\left(x-3\right)}=\frac{303}{1540}\)
\(\Rightarrow\)\(\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{x\left(x+3\right)}=\frac{303}{1540}\)
\(\Rightarrow\)\(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{x-1}\)
\(\Rightarrow\)\(\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)
\(\Rightarrow\)\(\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}\)
\(\Rightarrow\)\(\frac{1}{x+3}=\frac{308}{1540}-\frac{303}{1540}\)
\(\Rightarrow\)\(\frac{1}{x+3}=\frac{5}{1540}\)
\(\Rightarrow\)\(\frac{1}{x+3}=\)\(\frac{1}{308}\)
\(\Rightarrow\)\(x+3=308\)
\(\Rightarrow\)\(x=308-3\)
\(\Rightarrow\)\(x=305\)
16 tháng 4 2017
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
N
16 tháng 4 2017
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 \(7\)
\(3x=-6\)
\(x=-2\)
( 5,5.x - 44 : - 3/2 = 30
=> 5,5.x - 44 = 30. - 3/2
5,5.x - 44 =- 45
=> 5,5.x = ( - 45 )+44
5,5 .x = - 1
x =- 1 : 5,5
x =- 2/11
(5,5x-44):(-\(\frac{3}{2}\))=30
5,5x-44 =30.(\(-\frac{3}{2}\))=-45
5,5x =-45+44=-1
x =-1:5,5=\(-\frac{2}{11}\)