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22 tháng 9 2017

Bài 1: a) 4 . ( \(\dfrac{1}{3}\) - x ) + \(\dfrac{1}{2}\) = \(\dfrac{5}{6}\) . x

=> \(\dfrac{4}{3}\) - 4.x + \(\dfrac{1}{2}\) = \(\dfrac{5}{6}\) . x

=> \(\dfrac{11}{6}\) = \(\dfrac{29}{6}\) . x

=> x = \(\dfrac{11}{29}\) .

b) \(\dfrac{5}{2}\) - 3 . ( \(\dfrac{1}{3}\) - x ) = \(\dfrac{1}{4}\) - 7.x

=> \(\dfrac{1}{4}\) - \(\dfrac{3}{2}\) = 7.x + 3.x

=> \(\dfrac{-5}{4}\) = 10.x

=> x = \(\dfrac{-1}{8}\).

12 tháng 1 2018

2, \(\Rightarrow\left\{{}\begin{matrix}\\\dfrac{5}{4}x-\dfrac{7}{2}=0\\\dfrac{5}{8}x+\dfrac{3}{5}=0\\\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{14}{5}\\\\x=\dfrac{-24}{25}\\\end{matrix}\right.\)

20 tháng 8 2017

1.Tính

a.\(\dfrac{7}{23}\left[(-\dfrac{8}{6})-\dfrac{45}{18}\right]=\dfrac{7}{23}.-\dfrac{12}{6}=-\dfrac{7}{6}\)

b.\(\dfrac{1}{5}\div\dfrac{1}{10}-\dfrac{1}{3}(\dfrac{6}{5}-\dfrac{9}{4})=2-(-\dfrac{7}{20})=\dfrac{47}{20}\)

c.\(\dfrac{3}{5}.(-\dfrac{8}{3})-\dfrac{3}{5}\div(-6)=-\dfrac{3}{2}\)

d.\(\dfrac{1}{2}.(\dfrac{4}{3}+\dfrac{2}{5})-\dfrac{3}{4}.(\dfrac{8}{9}+\dfrac{16}{3})=-\dfrac{19}{5}\)

e.\(\dfrac{6}{7}\div(\dfrac{3}{26}-\dfrac{3}{13})+\dfrac{6}{7}.(\dfrac{1}{10}-\dfrac{8}{5})=-\dfrac{61}{7}\)

Bài 2

a.\(1^2_5x+\dfrac{3}{7}=\dfrac{4}{5}\)

\(x=\dfrac{13}{49}\)

b.\(\left|x-1,5\right|=2\)

Xảy ra 2 trường hợp

TH1

\(x-1,5=2\)

\(x=3,5\)

TH2

\(x-1,5=-2\)

\(x=-0,5\)

Vậy \(x=3,5\) hoặc \(x=-0,5\) .

Ngại làm quá trời ơi,lần sau bn tách ra nhá làm vậy mỏi tay quá.

20 tháng 8 2017

Ths bn nhé

28 tháng 8 2017

a) \(x+\dfrac{1}{3}=\dfrac{3}{4}\Leftrightarrow x=\dfrac{3}{4}-\dfrac{1}{3}\Leftrightarrow x=\dfrac{5}{12}\) vậy \(x=\dfrac{5}{12}\)

b) \(x-\dfrac{2}{5}=\dfrac{5}{7}\Leftrightarrow x=\dfrac{5}{7}+\dfrac{2}{5}\Leftrightarrow x=\dfrac{39}{35}\) vậy \(x=\dfrac{39}{35}\)

c) \(-x-\dfrac{2}{3}=\dfrac{-6}{7}\Leftrightarrow x=\dfrac{-2}{3}+\dfrac{6}{7}\Leftrightarrow x=\dfrac{4}{21}\) vậy \(x=\dfrac{4}{21}\)

d) \(\dfrac{4}{7}-x=\dfrac{1}{3}\Leftrightarrow x=\dfrac{4}{7}-\dfrac{1}{3}\Leftrightarrow x=\dfrac{5}{21}\) vậy \(x=\dfrac{5}{21}\)

2 tháng 9 2018

a) x + \(\dfrac{1}{3}\) = \(\dfrac{3}{4}\)

x = \(\dfrac{3}{4}\) - \(\dfrac{1}{3}\)

x = \(\dfrac{5}{12}\)

Vậy x = \(\dfrac{5}{12}\)

b) x - \(\dfrac{2}{5}\) = \(\dfrac{5}{7}\)

x = \(\dfrac{5}{7}\) + \(\dfrac{2}{5}\)

x = \(\dfrac{39}{35}\)

Vậy x = \(\dfrac{39}{35}\)

c) -x - \(\dfrac{2}{3}\) = \(-\dfrac{6}{7}\)

- x = \(-\dfrac{6}{7}\) + \(\dfrac{2}{3}\)

- x = \(-\dfrac{4}{21}\)

⇒ x = \(\dfrac{4}{21}\)

Vậy x = \(\dfrac{4}{21}\)

d) \(\dfrac{4}{7}\) - x = \(\dfrac{1}{3}\)

x = \(\dfrac{4}{7}\) - \(\dfrac{1}{3}\)

x = \(\dfrac{5}{21}\)

Vậy x = \(\dfrac{5}{21}\)

20 tháng 8 2017

Bn k có máy tính ạ/

20 tháng 8 2017

nóa pải ghi cách lm bn

5 tháng 8 2018

a. \(\dfrac{-39}{7}:x=26\)

x = \(\dfrac{-39}{7}:26\)

x = \(\dfrac{-3}{14}\)

b. \(x:\dfrac{13}{5}=\dfrac{7}{4}\)

x = \(\dfrac{7}{4}.\dfrac{13}{5}\)

x = \(\dfrac{91}{20}\)

c. x = \(\dfrac{-3}{5}-\dfrac{1}{2}\)

x = \(\dfrac{-11}{10}\)

d. \(x-\dfrac{3}{4}=\dfrac{9}{4}\)

x = \(\dfrac{9}{4}+\dfrac{3}{4}\)

x = 3

e. \(\dfrac{7}{8}:x=\dfrac{14}{3}\)

x = \(\dfrac{7}{8}:\dfrac{14}{3}\)

x = \(\dfrac{3}{16}\)

f. \(x:\dfrac{8}{3}=\dfrac{13}{3}\)

x = \(\dfrac{13}{3}.\dfrac{8}{3}\)

x = \(\dfrac{104}{9}\)

g. x = \(\dfrac{4}{10}-\dfrac{2}{5}\)

x = 0

chúc bạn học tốt banhquahahaleuleuok

14 tháng 2 2018

a) \(2\left(4x-30\right)-3\left(x+5\right)+4\left(x-10\right)=5\left(x+2\right)\)

\(\Leftrightarrow8x-60-3x+15+4x-40=5x+10\)

\(\Leftrightarrow9x-35=5x+10\)

\(\Leftrightarrow9x-5x=10+35\)

\(\Leftrightarrow4x=45\)

\(\Leftrightarrow x=\dfrac{45}{4}=11,25\)

b) \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\left(6x+1\right)\)

\(\Leftrightarrow\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=4x+\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{31}{60}+x=4x+\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{31}{60}-\dfrac{2}{3}=4x-x\)

\(\Leftrightarrow3x=\dfrac{1}{60}\)

\(\Leftrightarrow x=\dfrac{1}{180}\)

c) \(\dfrac{7}{3}-\left(2x-\dfrac{1}{3}\right)=\left(-2\dfrac{1}{6}+1\dfrac{1}{2}\right):0,25\)

\(\Leftrightarrow\dfrac{7}{3}-2x+\dfrac{1}{3}=-1\dfrac{2}{3}:\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{8}{3}-2x=\dfrac{-5}{3}.4\)

\(\Leftrightarrow\dfrac{8}{3}-2x=\dfrac{-20}{3}\)

\(\Leftrightarrow2x=\dfrac{8}{3}+\dfrac{20}{3}\)

\(\Leftrightarrow2x=\dfrac{28}{3}\)

\(\Leftrightarrow x=4\dfrac{2}{3}\)

d) \(0,75+\dfrac{5}{9}:x=5\dfrac{1}{2}\)

\(\Leftrightarrow\dfrac{3}{4}+\dfrac{5}{9}:x=\dfrac{11}{2}\)

\(\Leftrightarrow\dfrac{5}{9}:x=\dfrac{11}{2}-\dfrac{3}{4}\)

\(\Leftrightarrow\dfrac{5}{9}:x=\dfrac{19}{4}\)

\(\Leftrightarrow x=\dfrac{5}{9}:\dfrac{19}{4}\)

\(\Leftrightarrow x=\dfrac{20}{171}\)

30 tháng 11 2022

a: \(\Leftrightarrow\dfrac{5}{3}+\dfrac{4}{3}< x< 3+\dfrac{1}{5}+1+\dfrac{4}{5}\)

=>3<x<5

=>x=4

b: \(\Leftrightarrow\dfrac{1}{3}:2x=-5+\dfrac{1}{4}=-\dfrac{19}{4}\)

=>\(2x=\dfrac{1}{3}:\dfrac{-19}{4}=\dfrac{1}{3}\cdot\dfrac{-4}{19}=\dfrac{-4}{57}\)

=>x=-2/57

c: \(\Leftrightarrow x\cdot\dfrac{-3}{2}=\dfrac{10}{3}-\dfrac{6}{7}=\dfrac{70-18}{21}=\dfrac{52}{21}\)

=>\(x=\dfrac{-52}{21}:\dfrac{3}{2}=\dfrac{-52}{21}\cdot\dfrac{2}{3}=\dfrac{-104}{63}\)

d: \(\Leftrightarrow70+18< x< 120+70\)

=>88<x<190

hay \(x\in\left\{89;90;...;188;189\right\}\)

22 tháng 10 2017

a, \(\dfrac{1}{2}+\dfrac{2}{3}x=\dfrac{4}{5}\)

\(\Rightarrow\dfrac{2}{3}x=\dfrac{4}{5}-\dfrac{1}{2}\\ \Rightarrow\dfrac{2}{3}x=\dfrac{3}{10}\\ \Rightarrow x=\dfrac{3}{10}\cdot\dfrac{3}{2}\\ \Rightarrow x=\dfrac{9}{20}\)

b, \(x+\dfrac{1}{4}=\dfrac{4}{3}\)

\(\Rightarrow x=\dfrac{4}{3}-\dfrac{1}{4}\\ \Rightarrow x=\dfrac{13}{12}\)

c, \(\dfrac{3}{5}x-\dfrac{1}{2}=-\dfrac{1}{7}\)

\(\Rightarrow\dfrac{3}{5}x=-\dfrac{1}{7}-\dfrac{1}{2}\\ \Rightarrow\dfrac{3}{5}x=-\dfrac{9}{14}\\ \Rightarrow x=-\dfrac{9}{14}\cdot\dfrac{5}{3}\\ \Rightarrow x=\dfrac{15}{14}\)

d, \(\left|x-\dfrac{4}{5}\right|=\dfrac{3}{4}\)

\(\Rightarrow\left\{{}\begin{matrix}x-\dfrac{4}{5}=\dfrac{3}{4}\\x-\dfrac{4}{5}=-\dfrac{3}{4}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{3}{4}+\dfrac{4}{5}\\x=-\dfrac{3}{4}+\dfrac{4}{5}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{31}{20}\\x=\dfrac{1}{20}\end{matrix}\right.\)

e, \(lxl\) là j mk ko hiểu!

22 tháng 10 2017

a)2/3x=4/5-1/2

2/3x=3/10

x=3/10:2/3= 3/10.3/2=9/20