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12 tháng 8 2020

\(-\frac{17}{21}:\left(\frac{5}{4}-\frac{2}{5}\right)< x+\frac{4}{7}< 1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}\)

\(\Leftrightarrow-\frac{17}{21}:\frac{17}{20}< x+\frac{4}{7}< \frac{12}{12}-\frac{6}{12}+\frac{4}{12}-\frac{3}{12}\)

\(\Leftrightarrow-\frac{17}{21}.\frac{20}{17}< x+\frac{4}{7}< \frac{7}{12}\)

\(\Leftrightarrow-\frac{20}{21}< x+\frac{4}{7}< \frac{7}{12}\)

\(\Leftrightarrow-\frac{20}{21}< x< \frac{1}{84}\)

\(\Leftrightarrow-\frac{80}{84}< x< \frac{1}{84}\)

\(\Leftrightarrow-80< x< 1\Leftrightarrow x\in\left\{-79;-78;...;0\right\}\)

mà để Giá trị nguyên lớn nhất của x

\(\Rightarrow x=-1\)

12 tháng 8 2019

\(\left(x-\frac{3}{5}\right).\left(x+\frac{2}{7}\right)< 0\)

\(\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\\x+\frac{2}{7}>0\end{cases}\text{hoặc}\hept{\begin{cases}x-\frac{3}{5}>0\\x+\frac{2}{7}< 0\end{cases}}}\)

\(\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\\x>-\frac{2}{7}\end{cases}\text{hoặc}\hept{\begin{cases}x>\frac{3}{5}\\x< -\frac{2}{7}\end{cases}}}\)

\(\Rightarrow\orbr{\begin{cases}-\frac{2}{7}< x< \frac{3}{5}\\x\in\varnothing\end{cases}}\)

\(\Rightarrow-\frac{2}{7}< x< \frac{3}{5}\)

\(\Rightarrow x=0\)

Vậy x = 0

12 tháng 8 2019

\(\left(x-\frac{3}{5}\right)\cdot\left(x+\frac{2}{7}\right)< 0\)

TH1 : \(\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\\x+\frac{2}{7}>0\end{cases}}\)                 \(\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\\x>-\frac{2}{7}\end{cases}}\)              \(\Rightarrow\text{ }-\frac{2}{7}< x< \frac{3}{5}\)

TH2 : \(\Rightarrow\hept{\begin{cases}x-\frac{3}{5}>0\\x+\frac{2}{7}< 0\end{cases}}\)                 \(\Rightarrow\hept{\begin{cases}x>\frac{3}{5}\\x< -\frac{2}{7}\end{cases}}\)             \(\Rightarrow\text{ Không xảy ra}\)

                            Vì \(x\in Z\text{ }\Rightarrow\text{ }x=0\)

26 tháng 10 2016

\(\frac{11}{14}+\left|\frac{2}{7}-x\right|-\frac{5}{2}=\frac{4}{3}\)

\(\Leftrightarrow\frac{11}{14}+\left|\frac{2}{7}-x\right|=\frac{23}{6}\)

\(\Leftrightarrow\left|\frac{2}{7}-x\right|=\frac{64}{21}\)

\(\Leftrightarrow\frac{2}{7}-x=\pm\frac{64}{21}\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}\frac{2}{7}-x=\frac{64}{21}\\\frac{2}{7}-x=-\frac{64}{21}\end{array}\right.\Leftrightarrow\left[\begin{array}{nghiempt}x=-\frac{58}{21}\\x=\frac{10}{3}\end{array}\right.\)

\(x>0\)

Vậy \(x=\frac{10}{3}\)

 

26 tháng 10 2016

Thanks!

27 tháng 2 2020

                                                                 Bài giải

a, \(3\frac{1}{3}\text{ : }2\frac{1}{2}-1< x< 7\frac{2}{3}\cdot\frac{3}{7}+\frac{5}{2}\)

\(\frac{10}{3}\text{ : }\frac{5}{2}-1< x< \frac{23}{3}\cdot\frac{3}{7}+\frac{5}{2}\)

\(\frac{4}{3}-1< x< \frac{23}{7}+\frac{5}{2}\)

\(\frac{1}{3}< x< \frac{81}{14}\)

\(\Rightarrow\text{ }0,\left(3\right)< x< 5,78...\)

\(\Rightarrow\text{ }x\in\left\{1\text{ ; }2\text{ ; }3\text{ ; }4\text{ ; }5\right\}\)

b, \(\frac{1}{2}-\left(\frac{1}{3}+\frac{1}{4}\right)< x< \frac{1}{48}-\left(\frac{1}{16}-\frac{1}{6}\right)\)

\(\frac{1}{2}-\frac{7}{12}< x< \frac{1}{48}+\frac{5}{48}\)

\(-\frac{1}{12}< x< \frac{1}{8}\)

\(\Rightarrow\text{ }-0,08\left(3\right)< x< 0,125\)

\(\Rightarrow\text{ }x\in\varnothing\)

\(\Leftrightarrow\dfrac{1}{6}< \left|\dfrac{2}{7}-x\right|< \dfrac{3}{4}\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left|x-\dfrac{2}{7}\right|>\dfrac{1}{6}\\\left|x-\dfrac{2}{7}\right|< \dfrac{3}{4}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\in\left(-\infty;\dfrac{10}{84}\right)\cup\left(\dfrac{38}{84};+\infty\right)\\x\in\left(-\dfrac{39}{84};\dfrac{87}{84}\right)\end{matrix}\right.\)

\(\Leftrightarrow x\in\left(\dfrac{38}{84};\dfrac{87}{84}\right)\)