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QT
Quoc Tran Anh Le
Giáo viên
19 tháng 12 2017
b) \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)
\(\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{3}{4}\)
\(\dfrac{1}{4}:x=\dfrac{7}{20}\)
\(x=\dfrac{1}{4}:\dfrac{7}{20}=\dfrac{5}{7}\)
QT
Quoc Tran Anh Le
Giáo viên
19 tháng 12 2017
\(\left|x-3\right|=\dfrac{1}{2}\)
\(x-3=\pm\dfrac{1}{2}\)
| x-3 | \(\dfrac{1}{2}\) | \(-\dfrac{1}{2}\) |
| x | \(3\dfrac{1}{2}\) | \(2\dfrac{1}{2}\) |
LD
2
6 tháng 12 2017
\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:\left(0,1\right).x\)
\(\Rightarrow\dfrac{4}{3}:\dfrac{4}{5}=\dfrac{2}{3}:\dfrac{1}{10}.x\)
\(\Rightarrow\dfrac{4}{3}.\dfrac{5}{4}=\dfrac{2}{3}.10x\)
\(\Rightarrow\dfrac{5}{3}=\dfrac{2}{3}.10x\)
\(\Rightarrow10x=\dfrac{5}{3}:\dfrac{2}{3}\)
\(\Rightarrow10x=\dfrac{5}{2}\)
\(\Rightarrow x=\dfrac{5}{2}:10=\dfrac{1}{4}\)
Vậy \(x=\dfrac{1}{4}\)
LG
6 tháng 12 2017
\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:0,1x\Rightarrow\dfrac{4}{3}:\dfrac{3}{5}=\dfrac{2}{3}:\dfrac{1}{10}x\)
\(\Rightarrow\dfrac{4}{3}.\dfrac{5}{3}=\dfrac{2}{3}.10x\Rightarrow\dfrac{20}{9}=\dfrac{20}{3}x\Rightarrow x=\dfrac{1}{3}\)
Vậy...................................................
OT
17 tháng 7 2017
bài 1) ta có : \(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow2\left(x+y\right)=3\left(2x-y\right)\)
\(\Leftrightarrow2x+2y=6x-3y\Leftrightarrow4x=5y\Leftrightarrow\dfrac{x}{y}=\dfrac{5}{4}\)
vậy \(\dfrac{x}{y}=\dfrac{5}{4}\)
18 tháng 7 2017
bài 1
\(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow\dfrac{2.\dfrac{x}{y}-1}{\dfrac{x}{y}+1}=\dfrac{2.\dfrac{x}{y}+2-3}{\dfrac{x}{y}+1}=2-\dfrac{3}{\dfrac{x}{y}+1}=\dfrac{2}{3}\)
\(2-\dfrac{2}{3}=\dfrac{4}{3}=\dfrac{3}{\dfrac{x}{y}+1}\)
\(\left(\dfrac{x}{y}+1\right)=\dfrac{9}{4}\Rightarrow\dfrac{x}{y}=\dfrac{9}{4}-\dfrac{4}{4}=\dfrac{5}{4}\)
2 tháng 9 2017
a, \(\left|x+1,2\right|=0,5\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1,2=0,5\\x+1,2=-0,5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-0,7\\x=-1,7\end{matrix}\right.\)
Vậy ....
b, \(\left|x-\dfrac{1}{2}\right|+\dfrac{5}{6}=1\dfrac{1}{2}\)
\(\Leftrightarrow\left|x-\dfrac{1}{2}\right|=1\dfrac{1}{2}-\dfrac{5}{6}\)
\(\Leftrightarrow\left|x-\dfrac{1}{2}\right|=\dfrac{2}{3}\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=\dfrac{2}{3}\\x-\dfrac{1}{2}=\dfrac{-2}{3}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{6}\\x=\dfrac{-1}{6}\end{matrix}\right.\)
Vậy .....
c, \(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=\left|-3,2+\dfrac{2}{5}\right|\)
\(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=\left|-2,8\right|\)
\(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=2,8\)
\(\left|x-\dfrac{1}{2}\right|=2,8-\dfrac{4}{5}\)
\(\left|x-\dfrac{1}{2}\right|=2\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=2\\x-\dfrac{1}{2}=-2\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{-8}{5}\end{matrix}\right.\)
Vậy ...
NV
2
FT
9 tháng 10 2017
2 3x−125=12x+0,8(3)
2 3x−125=12x+\(\dfrac{5}{6}\)
=> \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{6}+\dfrac{7}{5}\)
=> \(\dfrac{1}{6}x=\dfrac{63}{30}\)
=> \(x=\dfrac{63}{30}:\dfrac{1}{6}\)
=> \(x=\dfrac{67}{5}\)
Vậy : x= 67 / 5
24 tháng 5 2022
a: \(\dfrac{-0.2}{x}=\dfrac{x}{-0.8}\)
\(\Leftrightarrow x^2=\dfrac{1}{5}\cdot\dfrac{4}{5}=\dfrac{4}{25}\)
=>x=2/5 hoặc x=-2/5
c: \(\dfrac{x-1}{x-2}=\dfrac{-3}{4}\)
=>4(x-1)=-3(x-2)
=>4x-4=-3x+6
=>7x=10
hay x=10/7
d: \(\dfrac{2-x}{5-x}=\dfrac{x+3}{x+2}\)
\(\Leftrightarrow\dfrac{x+3}{x+2}=\dfrac{x-2}{x-5}\)
\(\Leftrightarrow\left(x+3\right)\left(x-5\right)=\left(x-2\right)\left(x+2\right)\)
\(\Leftrightarrow x^2-2x-15=x^2-4\)
=>-2x=11
hay x=-11/2
29 tháng 10 2017
a) \(\dfrac{1,2}{x+3}=\dfrac{5}{4}\)
\(\Rightarrow\left(x+3\right).5=1,2.4\)
\(\Rightarrow\left(x+3\right).5=4,8\)
\(\Rightarrow x+3=4,8:5\)
\(\Rightarrow x+3=0,96\)
\(\Rightarrow x=-2,04\)
vậy \(x=-2,04\)
b)\(\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{1}{2}:\dfrac{4}{5}\)
\(\Rightarrow\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{5}{8}\)
\(\Rightarrow\dfrac{2x}{15}=\dfrac{3}{5}:\dfrac{5}{8}\)
\(\Rightarrow\dfrac{2x}{15}=\dfrac{24}{25}\)
\(\Rightarrow15.24=\left(2x\right).25\)
\(\Rightarrow360=\left(2x\right).25\)
\(\Rightarrow360:25=2x\)
\(\Rightarrow14,4=2x\)
\(\Rightarrow x=7,2\)
vậy \(x=7,2\)
29 tháng 10 2017
\(a,\dfrac{1,2}{x+3}=\dfrac{5}{4}\\ \left(x+3\right).5=1,2.4\\ 5x+8=4,8\\ 5x=4,8-8\\ 5x=-3,2\\ x=-3,2:5=-0,64\)
\(b,\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{1}{2}:\dfrac{4}{5}\\ \dfrac{2x}{15}=\dfrac{3}{5}\cdot\dfrac{4}{5}:\dfrac{1}{2}\\ \dfrac{2x}{15}=\dfrac{12}{25}.2\\ \dfrac{2x}{25}=\dfrac{24}{25}\\ 2x=\dfrac{24}{25}.5\\ 2x=\dfrac{24}{5}\\ x=\dfrac{24}{5}\cdot\dfrac{1}{2}=\dfrac{12}{5}\)
\(c,-\dfrac{4}{2,5}:3,5=1,5:x\\ x=3,5.1,5:\left(-\dfrac{4}{25}\right)\\ x=\dfrac{21}{4}\cdot\left(-\dfrac{25}{4}\right)=-\dfrac{525}{16}\)
\(d,0,12:3=2x:\dfrac{3}{5}\\ 2x=0,12\cdot\dfrac{3}{5}:3\\ 2x=\dfrac{9}{125}\cdot\dfrac{1}{3}\\ 2x=\dfrac{3}{125}\\ x=\dfrac{3}{125}\cdot\dfrac{1}{2}=\dfrac{3}{250}\)
24 tháng 6 2018
a)\(\dfrac{11}{12}-\left(\dfrac{2}{3}+x\right)=\dfrac{2}{3}\)
\(\dfrac{2}{3}+x=\dfrac{11}{12}-\dfrac{2}{3}\)
\(\dfrac{2}{3}+x=\dfrac{1}{4}\)
\(x=\dfrac{1}{4}-\dfrac{2}{3}\)
\(x=\dfrac{-5}{12}\)
Vậy x=\(\dfrac{-5}{12}\)
b)\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:0,1.x\)
\(\dfrac{4}{3}:0,8=\dfrac{20}{3}.x\)
\(\dfrac{5}{3}=\dfrac{20}{3}.x\)
\(x=\dfrac{5}{3}.\dfrac{3}{20}\)
\(x=\dfrac{1}{4}\)
Vậy \(x=\dfrac{1}{4}\)
S
24 tháng 6 2018
a, \(\dfrac{11}{12}-\left(\dfrac{2}{3}+x\right)=\dfrac{2}{3}\Rightarrow x=\dfrac{11}{12}-\dfrac{2}{3}-\dfrac{2}{3}=\dfrac{-5}{12}\)
b, \(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:0,1x\Rightarrow\dfrac{4}{3}:\dfrac{4}{5}=\dfrac{2}{3}:\dfrac{1}{10}x\Rightarrow\dfrac{4}{3}.\dfrac{1}{10}x=\dfrac{4}{5}.\dfrac{2}{3}\Rightarrow\dfrac{4}{3}.\dfrac{1}{10}x=\dfrac{8}{15}\Rightarrow x=\dfrac{8}{15}.\dfrac{3}{4}.10=4\)
tích trung tỉ bằng tihs ngoại tỉ là ra ý mà
\(\dfrac{x+1}{x+2}=\dfrac{0,8}{1,2}\) \(\Leftrightarrow0,8\left(x+2\right)=1,2\left(x+1\right)\)
\(\Leftrightarrow0,8x+1,6=1,2x+1,2\) \(\Leftrightarrow0,4x=0,4\Leftrightarrow x=1\)
vậy \(x=1\)