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

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16 tháng 4 2023

=> 2(2x +1) = 3(x-5) 

=> 4x + 2 = 3x - 15 

=> 4x - 3x = -15 - 2 

=> x = -17

16 tháng 4 2023

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

`=> 2(2x+1)=3(x-5)`

`=> 4x +2=3x-15`

`=> 4x-3x=-15-2`

`=> x= -17`

Vậy `x=-17`

`@ ` \(\text{Mạc Nhược Hàn}\)

3 tháng 5 2017

giúp mk với

21 tháng 6 2017

a) \(\dfrac{x+1}{32}=\dfrac{2}{x+1}\)

\(\Leftrightarrow\dfrac{x+1}{32}=\dfrac{2}{x+1}\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left(x+1\right)\left(x+1\right)=64\)

\(\Leftrightarrow\left(x+1\right)^2-64=0\)

\(\Leftrightarrow x^2+2x+1-64=0\)

\(\Leftrightarrow x^2+6x-63=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-2+16}{2}\\x=\dfrac{-2-16}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-9\end{matrix}\right.\left(đk:x\ne-1\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-9\end{matrix}\right.\)

Vậy \(x_1=-9;x_2=7\)

b) \(\dfrac{x+1}{5}=\dfrac{7}{x-1}\)

\(\Leftrightarrow\dfrac{x+1}{5}=\dfrac{7}{x-1}\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left(x+1\right)\left(x-1\right)=35\)

\(\Leftrightarrow\left(x+1\right)\left(x-1\right)-35=0\)

\(\Leftrightarrow x^2-1-35=0\)

\(\Leftrightarrow x^2-36=0\)

\(\Leftrightarrow x^2=36\)

\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\left(đk:x\ne1\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)

Vậy \(x_1=-6;x_2=6\)

c) \(\left|4,5-2x\right|:1\dfrac{7}{4}=\dfrac{11}{14}\)

\(\Leftrightarrow\left|4,5-2x\right|:\dfrac{11}{4}=\dfrac{11}{4}\)

\(\Leftrightarrow\left|4,5-2x\right|\cdot\dfrac{4}{11}=\dfrac{11}{14}\)

\(\Leftrightarrow\dfrac{4}{11}\cdot\left|4,5-2x\right|=\dfrac{11}{14}\)

\(\Leftrightarrow\left|4,5-2x\right|=\dfrac{121}{56}\)

\(\Leftrightarrow\left[{}\begin{matrix}4,5-2x=\dfrac{121}{56}\\4,5-2x=-\dfrac{121}{56}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{131}{112}\\x=\dfrac{373}{112}\end{matrix}\right.\)

Vậy \(x_1=\dfrac{131}{112};x_2=\dfrac{373}{112}\)

21 tháng 6 2017

a) \(\dfrac{x+1}{32}=\dfrac{2}{x+1}\)

\(\Rightarrow\left(x+1\right)\left(x+1\right)=32.2\)

\(\Rightarrow\left(x+1\right)^2=64\)

\(\Rightarrow\left(x+1\right)^2=8^2\)

\(\Rightarrow x+1=8\)

\(\Rightarrow x=8-1\)

\(\Rightarrow x=7\left(TM\right)\)

Vậy \(x=7\) là giá trị cần tìm

b) \(\dfrac{x+1}{5}=\dfrac{7}{x-1}\)

\(\Rightarrow\left(x+1\right)\left(x-1\right)=7.5\)

\(\Rightarrow\left[{}\begin{matrix}x+1=7\\x-1=5\end{matrix}\right.\) \(\Rightarrow x=6\left(TM\right)\)

Vậy \(x=6\) là giá trị cần tìm

c) \(\left|4,5-2x\right|:1\dfrac{7}{4}=\dfrac{11}{14}\)

\(\left|\dfrac{45}{10}-2x\right|:\dfrac{11}{4}=\dfrac{11}{4}\)

\(\left|\dfrac{9}{2}-2x\right|=\dfrac{11}{14}.\dfrac{11}{4}\)

\(\left|\dfrac{9}{2}-2x\right|=\dfrac{121}{56}\)

\(\Rightarrow\left[{}\begin{matrix}\dfrac{9}{2}-2x=\dfrac{121}{56}\\\dfrac{9}{2}-2x=\dfrac{-121}{56}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}2x=\dfrac{131}{56}\\2x=\dfrac{373}{56}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{131}{112}\\x=\dfrac{373}{112}\end{matrix}\right.\)

Vậy \(x\in\left\{\dfrac{131}{112};\dfrac{373}{112}\right\}\) là giá trị cần tìm

25 tháng 8 2017

a) x.(\(\dfrac{6}{7}\)+\(\dfrac{5}{6}\))=\(\dfrac{3}{4}\)

x.\(\dfrac{71}{42}\)=\(\dfrac{3}{4}\)

x=\(\dfrac{3}{4}\):\(\dfrac{71}{42}\)

x=\(\dfrac{63}{142}\)

25 tháng 8 2017

a.\(\dfrac{6}{7}x+\dfrac{5}{6}x=\dfrac{3}{4}\)

\(x.\left(\dfrac{6}{7}+\dfrac{5}{6}\right)=\dfrac{3}{4}\)

\(x.\dfrac{71}{42}=\dfrac{3}{4}\)

\(x=\dfrac{3}{4}:\dfrac{71}{42}\)

\(x=\dfrac{63}{142}\)

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

\(\dfrac{3}{5}:x=\dfrac{5}{4}-1\dfrac{1}{3}\)

\(\dfrac{3}{5}:x=\dfrac{-1}{12}\)

\(x=\dfrac{3}{5}:\dfrac{-1}{12}\)

\(x=\dfrac{-36}{5}\)

c. \(\left(\dfrac{4}{7}x-\dfrac{1}{3}\right):3\dfrac{1}{2}=0,5\)

\(\left(\dfrac{4}{7}x-\dfrac{1}{3}\right)=0,5:3\dfrac{1}{2}\)

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

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

\(\dfrac{4}{7}x=\dfrac{10}{21}\)

\(x=\dfrac{10}{21}:\dfrac{4}{7}\)

\(x=\dfrac{5}{6}\)

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

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

\(\dfrac{4}{5}-\dfrac{-11}{6}x=1\dfrac{1}{4}\)

\(\dfrac{-11}{6}x=\dfrac{4}{5}-1\dfrac{1}{4}\)

\(\dfrac{-11}{6}x=\dfrac{-9}{20}\)

\(x=\dfrac{-9}{20}:\dfrac{-11}{6}\)

\(x=\dfrac{27}{110}\)

có sai sót j xin bn thông cảm !

13 tháng 8 2017

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

\(\dfrac{2}{3}x-\dfrac{5}{6}=\dfrac{5}{4}\)

\(\dfrac{2}{3}x=\dfrac{5}{4}+\dfrac{5}{6}\)

\(\dfrac{2}{3}x=\dfrac{25}{12}\)

\(x=\dfrac{25}{12}:\dfrac{2}{3}\)

=>\(x=\dfrac{25}{8}\)

13 tháng 8 2017

a) \(\dfrac{2}{3}x-\dfrac{5}{6}=1\dfrac{1}{4}\) b) \(2\dfrac{1}{3}-\dfrac{4}{5}:x=0,2\)

\(\dfrac{2}{3}x-\dfrac{5}{6}=\dfrac{5}{4}\) \(\dfrac{7}{3}-\dfrac{4}{5}:x=\dfrac{1}{5}\)

\(\dfrac{2}{3}x=\dfrac{5}{4}-\dfrac{5}{6}\) \(\dfrac{4}{5}:x=\dfrac{7}{3}-\dfrac{1}{5}\)

\(\dfrac{2}{3}x=\dfrac{30}{24}-\dfrac{20}{24}\) \(\dfrac{4}{5}:x=\dfrac{35}{15}-\dfrac{3}{15}\)

\(\dfrac{2}{3}x=\dfrac{5}{12}\) \(\dfrac{4}{5}:x=\dfrac{32}{15}\)

\(x=\dfrac{5}{12}:\dfrac{2}{3}\) \(x=\dfrac{4}{5}:\dfrac{32}{15}\)

\(x=\dfrac{5}{12}:\dfrac{8}{12}\) \(x=\dfrac{4}{5}.\dfrac{15}{32}\)

\(x=\dfrac{5}{12}.\dfrac{12}{8}=\dfrac{5}{8}\) \(x=\dfrac{4.15}{5.32}\)

\(x=\dfrac{1.3}{1.8}=\dfrac{3}{8}\)

d)\(\left(\dfrac{4}{3}-\dfrac{1}{4}x\right)^3=\dfrac{-8}{27}\)

\(\left(\dfrac{4}{3}-\dfrac{1}{4}x\right)^3=\left(\dfrac{-2}{3}\right)^3\)

\(\Rightarrow\dfrac{4}{3}-\dfrac{1}{4}x=\dfrac{-2}{3}\)

\(\Rightarrow\dfrac{1}{4}x=\dfrac{4}{3}-\dfrac{-2}{3}\)

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

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

\(\Rightarrow x=2.4=8\)

12 tháng 9 2017

a.\(\dfrac{-4}{5}-\left(\dfrac{2}{3}x+1\dfrac{1}{4}\right)=\dfrac{2}{7}\)

\(\left(\dfrac{2}{3}x+1\dfrac{1}{4}\right)=\dfrac{-4}{5}-\dfrac{2}{7}=\dfrac{-38}{35}\)

\(\dfrac{2}{3}x=\dfrac{-38}{35}-1\dfrac{1}{4}\)

\(\dfrac{2}{3}x=\dfrac{-327}{140}\Rightarrow x=\dfrac{-327}{140}:\dfrac{2}{3}=\dfrac{-981}{280}\)

Vậy \(x=\dfrac{-981}{280}\)

b. \(\dfrac{5}{6}+\left(\dfrac{3}{4}-\dfrac{1}{2}:x\right)=\dfrac{-2}{3}\)

\(\left(\dfrac{3}{4}-\dfrac{1}{2}:x\right)=\dfrac{-2}{3}-\dfrac{5}{6}=\dfrac{-3}{2}\)

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

\(\dfrac{1}{2}:x=\dfrac{9}{4}\Rightarrow x=\dfrac{1}{2}:\dfrac{9}{4}=\dfrac{2}{9}\)

Vậy \(x=\dfrac{2}{9}\)

c. \(\left(\dfrac{4}{5}x-1\dfrac{1}{3}\right):\dfrac{3}{4}=0,7\)

\(\left(\dfrac{4}{5}x-1\dfrac{1}{3}\right)=0,7.\dfrac{3}{4}=\dfrac{21}{40}\)

\(\dfrac{4}{5}x=\dfrac{21}{40}+1\dfrac{1}{3}=\dfrac{223}{120}\)

\(\Rightarrow x=\dfrac{223}{120}:\dfrac{4}{5}=\dfrac{223}{96}\)

Vậy \(x=\dfrac{223}{96}\)

d. \(\dfrac{5}{6}-\dfrac{3}{4}x=1\dfrac{1}{3}+0,5x\)

\(0,5x+\dfrac{3}{4}x=\dfrac{5}{6}-1\dfrac{1}{3}\)

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

Vậy \(x=\dfrac{-2}{5}\)

13 tháng 7 2018

\(a,A=\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^{2017}}+\dfrac{1}{2^{2018}}\)

\(3A=1+\dfrac{1}{3}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{2016}}+\dfrac{1}{3^{2017}}\)

\(3A-A=1-\dfrac{1}{3^{2018}}\)

\(A=\dfrac{\left(1-\dfrac{1}{3^{2018}}\right)}{2}\)

\(b,B=1+5+5^2+5^3+...+5^{100}\)

\(5B=5+5^2+5^3+5^4+...+5^{100}+5^{101}\)

\(5B-B=1-5^{101}\)

\(B=\dfrac{\left(1-5^{101}\right)}{4}\)

\(.2.\)

\(a.\)

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

\(\Rightarrow2x=-\dfrac{5}{3}-\dfrac{1}{2}=-\dfrac{13}{6}\)

\(\Rightarrow x=-\dfrac{13}{6}:2=-\dfrac{13}{12}\)

Vậy : \(x=-\dfrac{13}{12}\)

\(b.\)

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

\(\Rightarrow\dfrac{3}{5}x=\dfrac{1}{7}-\dfrac{3}{5}=-\dfrac{16}{35}\)

\(\Rightarrow x=-\dfrac{16}{35}:\dfrac{3}{5}=-\dfrac{16}{21}\)

Vậy : \(x=-\dfrac{16}{21}\)

\(c.\)

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

\(\Rightarrow\dfrac{3}{4}x=-\dfrac{3}{5}-\dfrac{1}{2}=-\dfrac{11}{10}\)

\(\Rightarrow x=-\dfrac{11}{10}:\dfrac{3}{4}=-\dfrac{22}{15}\)

Vậy : \(x=-\dfrac{22}{15}\)

\(d.\)

\(-\dfrac{2}{15}-x=-\dfrac{3}{10}\)

\(\Rightarrow x=-\dfrac{2}{15}-\left(-\dfrac{3}{10}\right)=\dfrac{1}{6}\)

Vậy : \(x=\dfrac{1}{6}\)

9 tháng 3 2017

còn bài 1

4 tháng 8 2017

Giải:

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

\(\Leftrightarrow\dfrac{3}{5}x=\dfrac{-1}{2}+\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{3}{5}x=\dfrac{1}{6}\)

\(\Leftrightarrow x=\dfrac{1}{6}:\dfrac{3}{5}\)

\(\Leftrightarrow x=\dfrac{5}{18}\)

Vậy \(x=\dfrac{5}{18}\).

b) \(\left(\dfrac{1}{2}-x\right).\dfrac{2}{3}=\dfrac{1}{8}\)

\(\Leftrightarrow\dfrac{1}{2}-x=\dfrac{1}{8}:\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{1}{2}-x=\dfrac{3}{16}\)

\(\Leftrightarrow x=\dfrac{1}{2}-\dfrac{3}{16}\)

\(\Leftrightarrow x=\dfrac{5}{16}\)

Vậy \(x=\dfrac{5}{16}\).

c) \(\left|2x-\dfrac{3}{7}\right|-\dfrac{1}{2}=\dfrac{3}{4}\)

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

\(\Leftrightarrow\left|2x-\dfrac{3}{7}\right|=\dfrac{5}{4}\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-\dfrac{3}{7}=\dfrac{5}{4}\\2x-\dfrac{3}{7}=-\dfrac{5}{4}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{47}{28}\\2x=-\dfrac{23}{28}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{47}{56}\\x=-\dfrac{23}{56}\end{matrix}\right.\)

Vậy \(x=\dfrac{47}{56}\) hoặc \(x=-\dfrac{23}{56}\).

d) \(\dfrac{2x+1}{3}=\dfrac{x-5}{2}\)

\(\Leftrightarrow2\left(2x+1\right)=3\left(x-5\right)\)

\(\Leftrightarrow4x+2=3x-15\)

\(\Leftrightarrow4x-3x=-15-2\)

\(\Leftrightarrow x=-17\)

Vậy \(x=-17\).

Chúc bạn học tốt!!!

4 tháng 8 2017

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

\(\Rightarrow x=\dfrac{5}{18}\)

b) \(\left(\dfrac{1}{2}-x\right).\dfrac{2}{3}=\dfrac{1}{8}\)

\(\Rightarrow x=\dfrac{5}{16}\)

c) \(\left|2x-\dfrac{3}{7}\right|-\dfrac{1}{2}=\dfrac{3}{4}\)

\(\Rightarrow\left|2x-\dfrac{3}{7}\right|=\dfrac{5}{4}\)

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

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{47}{56}\\x=\dfrac{-23}{56}\end{matrix}\right.\)

d) \(\dfrac{2x+1}{3}=\dfrac{x-5}{2}\)

\(\Rightarrow4x+2=3x-15\)

\(\Rightarrow x=-17\).

1: =>7/3x=3+1/3-8-2/3=-5-1/3=-16/3

=>x=-16/3:7/3=-7/16

2: =>1/3|x-2|=4/5+3/7=28/35+15/35=43/35

=>|x-2|=129/35

=>x-2=129/35 hoặc x-2=-129/35

=>x=199/35 hoặc x=-59/35