a)x+3/6=7/2

x       =7/2-3/6

x     =3

b)2,8+(3x-5/6)=2/2/5

  14/5+(3x-5/6)=12/5

          (3x-5/6)=12/5-14/5

         3x+5/6=-2/5

        3x         =-2/5-5/6

       3x          =-37/30

          x         =-37/36:3

         x          =-37/90

CẢM ƠN PHAN THAO

Bạn có thể tham khảo trên mạng . 

|\(\frac32x\) + \(\frac12\)| = |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 \(x\in\) {\(\frac{116}{75}\); \(\frac{164}{25}\)}

4/7x - 2/3 = 1/5

=> 4/7x = 13/15

=> x = 91/60

vậy_

\(\frac{4}{7}x-\frac{2}{3}=\frac{1}{5}\)

\(\frac{4}{7}x=\frac{13}{15}\)

\(x=\frac{91}{60}\)

\(\frac{4}{5}+\frac{5}{7}:x=\frac{1}{6}\)

\(\frac{5}{7}:x=-\frac{19}{30}\)

\(x=-\frac{150}{133}\)

=.= hk tốt!!

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

Bài 1:

a; \(\dfrac{x}{3}\) = \(\dfrac{4}{y}\)

     \(xy\) = 12

12 = 2².3; Ư(12) = {-12; -6; -4; -3; -2; -1; 1; 2; 3; 4; 6;12}

Lập bảng ta có:

Theo bảng trên ta có các cặp \(x;y\) nguyên thỏa mãn đề bài là:

(\(x\)\(;y\)) =(-12; -1);(-6; -2);(-4; -3);(-2; -6);(-1; 12);(1; 12);(2;6);(3;4);(4;3);(6;2);(12;1)

b; \(\dfrac{x}{y}\) = \(\dfrac{2}{7}\)

    \(x\) = \(\dfrac{2}{7}\).y 

     \(x\) \(\in\)z ⇔ y ⋮ 7

   y = 7k;

   \(x\) = 2k 

Vậy \(\left\{{}\begin{matrix}x=2k\\y=7k;k\in z\end{matrix}\right.\) 

\(b,\frac{z}{7}=-\frac{11}{-28}\)

\(\Leftrightarrow z.\left(-28\right)=-11.7\)

\(\Leftrightarrow z.\left(-28\right)=-77\)

\(\Leftrightarrow z=\frac{11}{4}\)

\(a,-\frac{2}{3}=\frac{x-3}{-6}=\frac{10}{5-y}=\frac{4-2z}{9}\)

Xét :

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

\(\Leftrightarrow-2.\left(-6\right)=\left(x-3\right).3\)

\(\Leftrightarrow12=\left(x-3\right).3\)

\(\Leftrightarrow4=x-3\Leftrightarrow x=7\)

Xét 

\(-\frac{2}{3}=\frac{10}{5-y}\)

\(\Leftrightarrow-2.\left(5-y\right)=10.3\)

\(\Leftrightarrow-10+2y=30\)

\(\Leftrightarrow2y=40\Leftrightarrow y=20\)

Xét : 

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

\(\Leftrightarrow-2.9=\left(4-2z\right).3\)

\(\Leftrightarrow-18=\left(4-2z\right).3\)

\(\Leftrightarrow-6=4-2z\)

\(\Leftrightarrow10=2z\Leftrightarrow z=5\)

Vậy \(\left(x;y;z\right)=\left(7;20;5\right)\)

\(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\Rightarrow\frac{6x}{11.18}=\frac{9y}{2.18}=\frac{18z}{5.18}\)

\(\Rightarrow\frac{-x}{-33}=\frac{y}{4}=\frac{z}{5}=\frac{-x+y+z}{-33+4+5}=\frac{-120}{-24}=5\)

\(\Rightarrow x=165;y=20;z=25\)