\(\left\{\dfrac{-5< 0< -0,4}{x\in Z}\right\}\Rightarrow x\in\left\{-4;-3;-2;-1\right\}\)

chiu thôi leo nheo qua

chịu không viết được hỗn số

\(\Leftrightarrow\dfrac{41}{9}:\dfrac{41}{18}-7< x< \left(\dfrac{16}{5}:\dfrac{16}{5}+\dfrac{9}{2}\cdot\dfrac{76}{45}\right):\dfrac{-43}{2}\)

\(\Leftrightarrow-5< x< \left(1+\dfrac{38}{5}\right)\cdot\dfrac{-2}{43}=\dfrac{43}{5}\cdot\dfrac{-2}{43}=\dfrac{-2}{5}\)

mà x là số nguyên

nên \(x\in\left\{-4;-3;-2;-1\right\}\)

a: \(=12.7-\left(17.2+22.8\right)+\left(199.9-149.9\right)\)

\(=12.7-40+50=12.7+10=22.7\)

b: \(\Leftrightarrow\dfrac{41}{9}:\dfrac{41}{18}-7< x< \left(\dfrac{10}{3}:\dfrac{16}{5}+\dfrac{9}{2}\cdot\dfrac{76}{45}\right):\dfrac{-43}{2}\)

\(\Leftrightarrow-5< x< \dfrac{1037}{120}\cdot\dfrac{-2}{43}=\dfrac{-1037}{2580}\)

mà x là số nguyên

nên \(x\in\left\{-4;-3;-2\right\}\)

a: 2x(x-1/7)=0

=>x(x-1/7)=0

=>x=0 hoặc x=1/7

b: \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

\(\Leftrightarrow\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{3}{4}=\dfrac{8}{20}-\dfrac{15}{20}=\dfrac{-7}{20}\)

nên \(x=\dfrac{-1}{4}:\dfrac{7}{20}=\dfrac{-20}{4\cdot7}=\dfrac{-5}{7}\)

c: \(\Leftrightarrow\dfrac{41}{9}:\dfrac{41}{18}-7< x< \left(3.2:3.2+\dfrac{45}{10}\cdot\dfrac{31}{45}\right):\left(-21.5\right)\)

\(\Leftrightarrow2-7< x< \dfrac{\left(1+3.1\right)}{-21.5}\)

\(\Leftrightarrow-5< x< \dfrac{-41}{215}\)

mà x là số nguyên

nên \(x\in\left\{-4;-3;-2;-1\right\}\)

a )

\(4\dfrac{5}{9}:2\dfrac{5}{8}-7=-\dfrac{995}{189}=-5\) ( đã làm tròn )

\(\left(3\dfrac{1}{5}:3,2+4,5.1\dfrac{31}{45}\right):\left(-21\dfrac{1}{2}\right)\) \(=\dfrac{2}{5}=0\) ( đã làm tròn )

Ta có :

\(-5< x< 0\)

\(\Rightarrow x=\left\{-4;-3;-2;-1\right\}\)

b )

\(-\dfrac{17}{21}:\left(\dfrac{5}{4}-\dfrac{2}{5}\right)=-\dfrac{20}{21}=-1\) ( đã làm tròn )

\(1-\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}=\dfrac{7}{12}=1\) ( đã làm tròn )

Ta có : \(-1< x+0,6< 1\)

\(\Rightarrow x=\left\{-1;0\right\}\)

a) \(4\dfrac{5}{9}:2\dfrac{5}{8}-7< x< \left(3\dfrac{1}{5}:3,2+4,5\cdot1\dfrac{31}{45}\right):\left(-21\dfrac{1}{2}\right)\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>4\dfrac{5}{9}:2\dfrac{5}{8}-7\\x< \left(3\dfrac{1}{5}:3,2+4,5\cdot1\dfrac{31}{45}\right):\left(-21\dfrac{1}{2}\right)\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>-\dfrac{227}{36}\\x< -\dfrac{2}{5}\end{matrix}\right.\)

\(\Leftrightarrow-\dfrac{2}{5}>x>-\dfrac{227}{36}\)

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

\(\Leftrightarrow\left\{{}\begin{matrix}x+\dfrac{4}{7}>-\dfrac{17}{21}:\left(\dfrac{5}{4}-\dfrac{2}{5}\right)\\x+\dfrac{4}{7}< 1-\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>-\dfrac{32}{21}\\x< \dfrac{1}{84}\end{matrix}\right.\)

\(\Leftrightarrow\dfrac{1}{84}>x>-\dfrac{32}{21}\)

b) \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

\(\Rightarrow\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{2}{4}\)

\(\Rightarrow\dfrac{1}{4}:x=-\dfrac{1}{10}\)

\(\Rightarrow x=\dfrac{1}{4}:\left(-\dfrac{1}{10}\right)\)

\(\Rightarrow x=-\dfrac{3}{2}\)