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16 tháng 2 2015

c. khi và chỉ khi \(\frac{3}{5}\cdot\frac{1}{x}=\frac{1}{3}-\frac{4}{15}=\frac{1}{15}\)

                        \(\frac{1}{x}=\frac{1}{15}\cdot\frac{5}{3}=\frac{1}{9}\)

suy ra x=9

16 tháng 2 2015

a,7/6x=3/5-1/30

7/6x=17/30

x=17/30:7/6

x=17/35

b,(-9/2-2x).11/7=11/4

-9/2-2x=11/4:11/7

-9/2-2x=7/4

2x=-9/2-7/4

2x=-25/4

x=-25/4:2

x=-25/8

c,9

d,x=-2

e,2.8=x.x=x2

16=x2=>x=4 hoặc -4

\(a)x+30\%x=-1,31\)

\(\Leftrightarrow x+\frac{3x}{10}=-1,31\)

\(\Leftrightarrow10x+3x=-13,1\)

\(\Leftrightarrow13x=-13,1\Leftrightarrow x=-\frac{131}{130}\)

\(b)\left(x-\frac{1}{2}\right):\frac{1}{3}+\frac{5}{7}=9\frac{5}{7}\)

\(\Leftrightarrow\frac{2x-1}{2}.3+\frac{5}{7}=\frac{68}{7}\)

\(\Leftrightarrow\frac{6x-3}{2}=\frac{63}{7}\)

\(\Leftrightarrow\frac{6x-3}{2}=9\)

\(\Leftrightarrow6x-3=18\)

\(\Leftrightarrow x=\frac{7}{2}\)

26 tháng 6 2017

\(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)

\(\frac{3}{2}x-\frac{2}{3}=\frac{4}{9}\)

\(\frac{3}{2}x=\frac{4}{9}+\frac{2}{3}\)

\(\frac{3}{2}x=\frac{10}{9}\)

\(x=\frac{10}{9}:\frac{3}{2}\)

\(x=\frac{20}{27}\)

Vậy x=\(\frac{20}{27}\)

\(\left(\frac{9}{11}-x\right):\frac{-10}{11}=1-\frac{4}{5}\)

\(\left(\frac{9}{11}-x\right):\frac{-10}{11}=\frac{1}{5}\)

\(\frac{9}{11}-x=\frac{1}{5}\cdot\frac{-10}{11}\)

\(\frac{9}{11}-x=\frac{-2}{11}\)

\(x=\frac{9}{11}-\frac{-2}{11}\)

\(x=1\)

Vậy x=1

\(\frac{-11}{12}\cdot x+\frac{3}{4}=\frac{-1}{6}\)

\(\frac{-11}{12}\cdot x=\frac{-1}{6}-\frac{3}{4}\)

\(\frac{-11}{12}\cdot x=\frac{21}{12}\)

\(x=\frac{-21}{11}\)

Vậy x=\(\frac{-21}{11}\)

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

\(\frac{3}{2}+x=\frac{-5}{4}-\frac{9}{2}\)

\(\frac{3}{2}+x=\frac{23}{4}\)

\(x=\frac{17}{4}\)

Vậy x=\(\frac{17}{4}\)

\(\left(\frac{3}{4}-x:\frac{2}{15}\right)\cdot\frac{1}{5}=-2,6\)

\(\frac{3}{4}-x:\frac{2}{15}=\frac{-13}{5}:\frac{1}{5}\)

\(\frac{3}{4}-x:\frac{2}{15}=-13\)

\(x:\frac{2}{15}=\frac{3}{4}-\left(-13\right)\)

\(x:\frac{2}{15}=\frac{45}{4}\)

\(x=\frac{3}{2}\)

Vậy x=\(\frac{3}{2}\)

\(3-\left(\frac{1}{6}-x\right)\cdot\frac{2}{3}=\frac{2}{3}\)

\(3-\left(\frac{1}{6}-x\right)=\frac{2}{3}:\frac{2}{3}\)

\(3-\left(\frac{1}{6}-x\right)=1\)

\(\frac{1}{6}-x=2\)

\(x=\frac{1}{6}-2\)

\(x=\frac{-11}{6}\)

Vậy x=\(\frac{-11}{6}\)

\(\left(1-2x\right)\cdot\frac{4}{5}=\left(-2\right)^3\)

\(1-2x=\frac{-1}{10}\)

\(2x=1-\frac{-1}{10}\)

\(2x=\frac{11}{10}\)

\(x=\frac{11}{20}\)

Vậy x=\(\frac{11}{20}\)

\(\frac{1}{6}-\left|\frac{1}{2}\cdot x-\frac{1}{3}\right|=\frac{1}{8}\)

\(\left|\frac{1}{2}\cdot x-\frac{1}{3}\right|=\frac{7}{12}\)

\(\Rightarrow\frac{1}{2}x-\frac{1}{3}=\frac{7}{12}\)                                                         \(\frac{1}{2}x-\frac{1}{3}=\frac{-7}{12}\)

\(\frac{1}{2}x=\frac{11}{12}\)                                                                        \(\frac{1}{2}x=\frac{-1}{4}\)

\(x=\frac{11}{6}\)                                                                              \(x=\frac{-1}{2}\)

Vậy \(x\in\left\{\frac{11}{6};\frac{-1}{2}\right\}\)

26 tháng 6 2017

\(\frac{3}{2}x-\frac{2}{3}=\frac{2}{3}:\frac{3}{2}\)

\(\frac{3}{2}x=\frac{4}{9}+\frac{6}{9}\)

\(\frac{3}{2}x=\frac{10}{9}\)

\(x=\frac{10}{9}:\frac{3}{2}\)

\(x=\frac{20}{27}\)

tk mình đi mình làm nốt cho hjhj ^^

6 tháng 6 2016

a) (1/2(2/− 2x0

\(\Rightarrow\left[\begin{array}{nghiempt}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=-\frac{1}{2}\\2x=\frac{2}{3}\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=-\frac{1}{2}\\x=\frac{1}{3}\end{array}\right.\)

b) \(\left(x.6\frac{2}{7}+\frac{3}{7}\right).2\frac{1}{5}-\frac{3}{7}=-2\)

\(\Rightarrow\left(x.\frac{44}{7}+\frac{3}{7}\right).\frac{11}{5}=-2+\frac{3}{7}\)

\(\Rightarrow\left(x.\frac{44}{7}+\frac{3}{7}\right).\frac{11}{5}=-\frac{11}{7}\)

\(\Rightarrow x.\frac{44}{7}+\frac{3}{7}=-\frac{11}{7}:\frac{11}{5}=-\frac{11}{7}.\frac{5}{11}\)

\(\Rightarrow x.\frac{44}{7}+\frac{3}{7}=-\frac{5}{7}\)

\(\Rightarrow x.\frac{44}{7}=-\frac{5}{7}-\frac{3}{7}\)

\(\Rightarrow x.\frac{44}{7}=-\frac{8}{7}\)

\(\Rightarrow x=-\frac{8}{7}:\frac{44}{7}=-\frac{8}{7}.\frac{7}{44}\)

\(\Rightarrow x=-\frac{2}{11}\)

6 tháng 6 2016

c) \(x.3\frac{1}{4}+\left(-\frac{7}{6}\right).x-1\frac{2}{3}=\frac{5}{12}\)

\(\Rightarrow x\left(3\frac{1}{4}-\frac{7}{6}\right)=\frac{5}{12}+\frac{5}{3}\)

\(\Rightarrow x\left(\frac{13}{4}-\frac{7}{6}\right)=\frac{25}{12}\)

\(\Rightarrow x.\frac{25}{12}=\frac{25}{12}\)

\(\Rightarrow x=\frac{25}{12}:\frac{25}{12}\)

\(\Rightarrow x=1\)

d) \(5\frac{8}{17}:x+\left(-\frac{4}{17}\right):x+3\frac{1}{7}:17\frac{1}{3}=\frac{4}{11}\)

\(\Rightarrow\left(5\frac{8}{17}-\frac{4}{17}\right):x+\frac{22}{7}:\frac{52}{3}=\frac{4}{11}\)

\(\Rightarrow5\frac{4}{17}:x+\frac{33}{182}=\frac{4}{11}\)

\(\Rightarrow\frac{89}{17}:x=\frac{4}{11}-\frac{33}{182}\)

\(\Rightarrow\frac{89}{17}:x=\frac{365}{2002}\)

\(\Rightarrow x=\frac{89}{17}:\frac{365}{2002}\)

\(\Rightarrow x\approx28,7\) (số hơi lẻ)

e) \(\frac{17}{2}-\left|2x-\frac{3}{4}\right|=-\frac{7}{4}\)

\(\Rightarrow\left|2x-\frac{3}{4}\right|=\frac{17}{2}+\frac{7}{4}\)

\(\Rightarrow\left|2x-\frac{3}{4}\right|=\frac{41}{4}\)

\(\Rightarrow\left[\begin{array}{nghiempt}2x-\frac{3}{4}=\frac{41}{4}\\2x-\frac{3}{4}=-\frac{41}{4}\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}2x=11\\2x=-\frac{19}{2}\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{11}{2}\\x=-\frac{19}{4}\end{array}\right.\)

19 tháng 4 2019

Câu a \(\left|2x-\frac{1}{3}\right|+\frac{5}{6}=1\)

19 tháng 4 2019

g) \(\left(x+\frac{1}{2}\right)\left(\frac{2}{3}-2x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{2}\\x=\frac{1}{3}\end{cases}}\)

Vây \(x\in\left\{\frac{-1}{2};\frac{1}{3}\right\}\)

2 tháng 8 2017

 mik ko chép lại đề, mik làm luôn: 

a)  x - \(\frac{31}{36}=\frac{-13}{38}\)

x = \(\frac{-13}{18}+\frac{31}{36}\)

\(x=\frac{5}{36}\)

b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)

\(\frac{11}{7}-x=\frac{3}{7}\)

x = \(\frac{11}{7}-\frac{3}{7}\)

x = 8/7

c) x + 3/11 = 23/44

x = 23/44 - 3/11

x = 1/4

d) \(\frac{1}{12}-x=\frac{-11}{9}\)

x = \(\frac{1}{12}+\frac{11}{9}\)

x = 47/36

e) \(x-\frac{2}{3}=\frac{-17}{3}\)

x= -17/3 + 2/3

x = -5 

f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)

x - 1/2 = 3/4

x = 3/4 + 1/2 

x = 5/4

g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)

2x + 3/8 = -3 / 8

2x = -3/8 - 3/8 

2x = -9/8

x = -9/8.1/2 

x = -9/16

h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)

x  - \(\frac{x}{3}=\frac{1}{12}\)

x = \(\frac{1}{12}+\frac{x}{3}\)

x = \(\frac{1+4x}{12}\)

=> 12x = 1+4x

12x - 4x = 1

8x = 1

x = 1/8 

2 tháng 8 2017

Trả lời nhanh gọn lẹ nhé, mình k cho :)

16 tháng 7 2021

mình cần gấp nhé