a/ \(\frac{x+2}{27}=\frac{x}{9}\)

=> 9(x + 2) = 27x

=> 9x + 18 = 27x

=> 9x + 18 - 27x = 0

=> 9x - 27x + 18 = 0

=> -18x = -18

=> x = 1

b/ \(\frac{-7}{x}=\frac{21}{34-x}\)

=> -7(34 - x) = 21x

=>  -238 + 7x = 21x

=> 21x - 7x = -238

=> -14x = 238

=> x = -17

c) \(\frac{-8}{15}< \frac{x}{40}< \frac{-7}{15}\)

Ta có BCNN(15,40,15) = 120

=> \(\frac{-64}{120}< \frac{3x}{120}< \frac{-56}{120}\)

=> -64 < 3x < -56

=> x \(\in\){ -19;-20;-21}

Câu d tương tự

d) \(\frac{-1}{2}< \frac{x}{18}< \frac{-1}{3}\)

\(\Leftrightarrow\frac{-9}{18}< \frac{x}{18}< \frac{-6}{18}\)

\(\Leftrightarrow-9< x< -6\)

\(\Rightarrow x\in\left\{-8;-7\right\}\)

\(x\times\frac{6}{25}=\frac{15}{-13}\)

x=\(\frac{15}{-13}\div\frac{6}{25}\)

x=\(-\frac{125}{26}\)

các câu còn lại làm tương tự nha!!!

\(1.x.\frac{6}{25}=\frac{15}{-13}\\ x=\frac{15}{-13}:\frac{6}{25}\\ x=-\frac{125}{26}\)

\(2.x:\frac{4}{10}=\frac{13}{-45}+\frac{8}{15}\\ x:\frac{4}{10}=\frac{11}{45}\\ x=\frac{11}{45}.\frac{4}{10}\\ x=\frac{22}{225}\)

\(3.\frac{3}{8}-\frac{1}{6}.x=\frac{1}{4}\\ \frac{1}{6}.x=\frac{3}{8}-\frac{1}{4}\\ \frac{1}{6}.x=\frac{1}{8}\\ x=\frac{1}{8}:\frac{1}{6}\\ x=\frac{3}{4}\)

\(4.\frac{1}{3}+\frac{1}{2}:x=-4\\ \frac{1}{2}:x=-4-\frac{1}{3}=-\frac{13}{3}\\ x=\frac{1}{2}:\left(-\frac{13}{3}\right)=-\frac{3}{26}\)

\(5.x+\frac{7}{12}=\frac{17}{18}-\frac{1}{9}=\frac{5}{6}\\ x=\frac{5}{6}-\frac{7}{12}\\ x=\frac{1}{4}\)

Trả lời

a)2x-15=17

   2x     =17-15

  2x      =2

   x       =2:2

   x       =1

b)3 1/8-1/2x=0,5

    25/8-1/2x=1/2

            1/2x=25/8-1/2

            1/2x=21/8

                 x=21/8.2/1

                 x=21/4

c)8 1/4x+2 1/3=20

   33/4x+7/3     =20

   33/4x            =20-7/3

   33/4x            =53/3

          x            =53/3.4/33

         x             =...

a) 2x - 15 = 17

2x = 17 + 15

2x = 32

x = 32 : 2 

x = 16

Vậy x = 16

b) \(3\frac{1}{3}-\frac{1}{2}x=0,5\)

\(\frac{10}{3}-\frac{1}{2}x=\frac{1}{2}\)

\(\frac{1}{2}x=\frac{10}{3}-\frac{1}{2}\)

\(\frac{1}{2}x=\frac{17}{6}\)

\(x=\frac{17}{6}:\frac{1}{2}\)

\(x=\frac{17}{3}\)

Vậy x = 17/3

c) \(8\frac{1}{4}x+2\frac{1}{3}=20\)

\(\frac{33}{4}x+\frac{7}{3}=20\)

\(\frac{33}{4}x=20-\frac{7}{3}\)

\(\frac{33}{4}x=\frac{53}{3}\)

\(x=\frac{53}{3}:\frac{33}{4}\)

\(x=\frac{212}{99}\)

Vậy x = 212/99

=))

a.2/3 + 1/3 - x= 3/5

=> 1-x = 3/5

=>  x = 1-3/5= 2/5

b. 1/8/15 - 2/3x = 0,2

=> 2/3x= 23/15 - 1/5= 4/3

=> x= 4/3 : 2/3=2

c. 2/3x -3/2x = 5/12

=> x( 2/3 - 3/2) = 5/12

=> x. -5/6 = 5/12

=> x= 5/12 : -5/6

=> x= -1/2

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

=> 1 - x = 3/5

=> x = 1 - 3/5

     x = 2/5

b) \(1\frac{8}{15}-\frac{2}{3}x=0,2\)

=> 23/15 - 2/3x = 0,2

=> 2/3x = 23/15 - 0,2

    2/3x = 1,333333333

=>x = 1,333333333 : 2/3

    x = 2

c) ???

|\(\frac32x\) + \(\frac12\)| = |4\(x\) - 1|

\(\left[\begin{array}{l}\frac32x+\frac12=-4x+1\\ \frac32x+\frac12=4x-1\end{array}\right.\)

\(\left[\begin{array}{l}\frac32x+4x=1-\frac12\\ \frac32x-4x=-1-\frac12\end{array}\right.\)

\(\left[\begin{array}{l}\frac{11}{2}x=\frac12\\ -\frac52x=-\frac32\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac12:\frac{11}{2}\\ x=-\frac32:\frac{-5}{2}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac12\times\frac{2}{11}\\ x=-\frac32\times\frac{-2}{5}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{1}{11}\\ x=\frac35\end{array}\right.\)

Vậy \(x\in\) {\(\frac{1}{11};\frac35\)}

|\(\frac54x\) - \(\frac72\)| - |\(\frac58x\) + \(\frac35\)| = 0

|\(\frac54x\) - \(\frac72\)| = |\(\frac58x\) + \(\frac35\)|

\(\left[\begin{array}{l}\frac54x-\frac72=-\frac58x-\frac35\\ \frac54x-\frac72=\frac58x+\frac35\end{array}\right.\)

\(\left[\begin{array}{l}\frac54x+\frac58x=\frac72-\frac35\\ \frac54x-\frac58x=\frac72+\frac35\end{array}\right.\)

\(\left[\begin{array}{l}\frac{15}{8}x=\frac{29}{20}\\ \frac58x=\frac{41}{10}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{29}{10}:\frac{15}{8}\\ x=\frac{41}{10}:\frac58\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{116}{75}\\ x=\frac{164}{25}\end{array}\right.\)

Vậy \(x\in\) {\(\frac{116}{75}\); \(\frac{164}{25}\)}

a) \(\frac{9}{20}\)                                                   c) \(\frac{-55}{4}\)                                                                                                                                 

b) \(\frac{116}{75}\)                                                d) \(\frac{-76}{45}\)

đúng hết đấy nhé mình tính kĩ lắm ko sai đâu

       chúc may mắn