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19 tháng 8 2016

\(\left|x+\frac{1}{2}\right|+\left|x+\frac{1}{3}\right|+\left|x+\frac{1}{4}\right|=4x.\)

Điều kiện \(4x\ge0\)nên 

\(x+\frac{1}{2}+x+\frac{1}{3}+x+\frac{1}{4}=4x\)

\(\Leftrightarrow3x+\frac{13}{12}=4x\)

\(\Leftrightarrow4x-3x=\frac{13}{12}\)

\(\Leftrightarrow x=\frac{13}{12}\)

30 tháng 10 2019

a) \(\left|2-x\right|+x=-3\\ \Rightarrow\left|2-x\right|=-3-x\left(ĐK:-3-x\ge0\right)\\ \Rightarrow\left[{}\begin{matrix}2-x=-3-x\\2-x=3+x\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x-x=-3-2\\-x-x=3-2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}0=-5\left(\text{vô lí}\right)\\-2x=1\end{matrix}\right.\Rightarrow x=\frac{-1}{2}\left(ktm\text{ }-3-x\ge0\right)\)

Vậy \(x\in\varnothing\)

b) \(\left|x-1\right|+1=2x-3\\ \Rightarrow\left|x-1\right|=2x-4\left(ĐK:2x-4\ge0\right)\\ \Rightarrow\left[{}\begin{matrix}x-1=2x-4\\x-1=-2x+4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x-x=4-1\\x+2x=1+4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=3\left(t/m\right)\\3x=5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\left(t/m\right)\\x=\frac{5}{3}\left(ktm\right)\end{matrix}\right.\)

Vậy x = 3

c) \(\left|\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}\right|=\left|2x-2+\frac{1}{3}\right|\\ \Rightarrow\left[{}\begin{matrix}\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}=2x-2+\frac{1}{3}\\\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}=-2x+2-\frac{1}{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x-\frac{4}{3}x=2-\frac{1}{3}-\frac{4}{3}+\frac{1}{2}\\\frac{4}{3}x+2x=\frac{4}{3}-\frac{1}{2}+2-\frac{1}{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}\frac{2}{3}x=\frac{5}{6}\\\frac{10}{3}x=\frac{5}{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{5}{4}\\x=\frac{3}{4}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{5}{4};\frac{3}{4}\right\}\)

24 tháng 10 2016

\(\left|x-\frac{1}{3}\right|+\frac{4}{5}=\left|\left(-3,2\right)+\frac{2}{5}\right|\)

 \(\left|x-\frac{1}{3}\right|+\frac{4}{5}=\frac{14}{5}\)

            \(\left|x-\frac{1}{3}\right|=2\)  

=> \(x-\frac{1}{3}=2\) hoặc \(x-\frac{1}{3}=-2\)

                x    = \(\frac{7}{3}\)                  x    = \(\frac{-5}{3}\)

Vậy x = \(\frac{7}{3}\)hoặc x    = \(\frac{-5}{3}\)

4 tháng 11 2019

3)

a)\(\left(x+5\right)^3=-64\\ \Leftrightarrow\left(x+5\right)^3=\left(-4\right)^3\\ \Leftrightarrow x+5=-4\\ \Leftrightarrow x=-9\)

Vậy x = -9

b)\(\left(2x-3\right)^2=9\\ \Leftrightarrow\left(2x-3\right)^2=\left(\pm3\right)^2\\ \Rightarrow2x-3\in\left\{3;-3\right\}\Rightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)

Vậy...

c)\(x^2+1=82\\ \Leftrightarrow x^2=81\\ \Leftrightarrow x^2=\left(\pm9\right)^2\\ \Rightarrow x\in\left\{9;-9\right\}\)

Vậy...

d)\(x^2+\frac{7}{4}=\frac{23}{4}\\ \Leftrightarrow x^2=16\\ \Leftrightarrow x^2=\left(\pm4\right)^2\\ \Rightarrow x\in\left\{4;-4\right\}\)

Vậy...

e)\(\left(2x+3\right)^2=25\\ \Leftrightarrow\left(2x+3\right)^2=\left(\pm5\right)^2\\ \Rightarrow2x+3\in\left\{5;-5\right\}\\ \Rightarrow\left[{}\begin{matrix}2x+3=5\\2x+3=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-4\end{matrix}\right.\)

Vậy...

4 tháng 11 2019

3)

a) \(\left(x+5\right)^3=-64\)

\(\Rightarrow\left(x+5\right)^3=\left(-4\right)^3\)

\(\Rightarrow x+5=-4\)

\(\Rightarrow x=\left(-4\right)-5\)

\(\Rightarrow x=-9\)

Vậy \(x=-9.\)

b) \(\left(2x-3\right)^2=9\)

\(\Rightarrow2x-3=\pm3.\)

\(\Rightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6:2\\x=0:2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)

Vậy \(x\in\left\{3;0\right\}.\)

c) \(x^2+1=82\)

\(\Rightarrow x^2=82-1\)

\(\Rightarrow x^2=81\)

\(\Rightarrow\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)

Vậy \(x\in\left\{9;-9\right\}.\)

d) \(x^2+\frac{7}{4}=\frac{23}{4}\)

\(\Rightarrow x^2=\frac{23}{4}-\frac{7}{4}\)

\(\Rightarrow x^2=4\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)

Vậy \(x\in\left\{2;-2\right\}.\)

Chúc bạn học tốt!

3 tháng 8 2017

\(\left|x\right|=\left|\frac{1}{8}\right|\)

\(x\in\left\{\frac{1}{8};-\frac{1}{8}\right\}\)

24 tháng 6 2017

\(x=-\frac{1}{7}\Leftrightarrow\left|x\right|=\frac{1}{7}\)

\(x=-3\frac{5}{1}\Leftrightarrow x=-8\Leftrightarrow\left|x\right|=8\)

\(x=0\Leftrightarrow\left|x\right|=0\)