bài 1 : a,ta có 3/x-1 =4/y-2=5/z-3 =>  x-1/3=y-2/4=z-3/5 

áp dụng .... => x-1+y-2+z-3 / 3+4+5 = x+y+z-1-2-3/3+4+5 = 12/12=1

do x-1/3 = 1 => x-1 = 3 => x= 4 ( tìm y,z tương tự

Bài 1: 

a) Ta có: 3/x - 1 = 4/y - 2 = 5/z - 3 => x - 1/3 = y - 2/4 = z - 3/5 áp dụng ... =>x - 1 + y - 2 + z - 3/3 + 4 + 5 = x + y + z - 1 - 2 - 3/3 + 4 + 5 = 12/12 = 1 do x - 1/3 = 1 => x - 1 = 3 => x = 4 ( tìm y, z tương tự )

cũng dễ thôi

a) Ta có: \(x+\dfrac{1}{3}=\dfrac{2}{6}\)

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

hay x=0

Vậy: x=0

b) Ta có: \(x-\dfrac{1}{4}=\dfrac{1}{-2}\)

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

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

Vậy: \(x=-\dfrac{1}{4}\)

c) Ta có: \(\dfrac{-1}{6}=\dfrac{3}{2}x\)

\(\Leftrightarrow x=\dfrac{-1}{6}:\dfrac{3}{2}=\dfrac{-1}{6}\cdot\dfrac{2}{3}\)

hay \(x=\dfrac{-1}{9}\)

Vậy: \(x=\dfrac{-1}{9}\)

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

\(x=0\)

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

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

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

c. \(\dfrac{-1}{6}=\dfrac{3}{2x}\)

\(-2x=18\)

\(x=-9\)

d. \(\dfrac{4}{5}=\dfrac{-12}{9-x}\)

\(4.\left(9-x\right)=-60\)

\(9-x=-15\)

\(x=24\)

\(e.\dfrac{x+1}{3}=\dfrac{3}{x+1}\)

\(\left(x+1\right)^2=9\)

\(\left[{}\begin{matrix}x+1=-3\\x+1=3\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-4\\x=2\end{matrix}\right.\)

f.\(\dfrac{x-1}{-4}=\dfrac{-4}{x-1}\)

\(\left(x-1\right)^2=16\)

\(\left[{}\begin{matrix}x-1=4\\x-1=-4\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)

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

    \(x\) \(\times\) \(\dfrac{1}{2}\)       = \(\dfrac{5}{6}\) + \(\dfrac{3}{4}\)

   \(x\)   \(\times\) \(\dfrac{1}{2}\)      =  \(\dfrac{19}{12}\)

   \(x\)                = \(\dfrac{19}{12}\) : \(\dfrac{1}{2}\)

  \(x\)                 =   \(\dfrac{19}{6}\)

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

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

   \(x\) : \(\dfrac{1}{2}\)        = \(\dfrac{19}{12}\)

   \(x\)              =   \(\dfrac{19}{12}\)  \(\times\) \(\dfrac{1}{2}\) 

   \(x\)              =  \(\dfrac{19}{24}\)

c, \(x\) \(\times\) \(\dfrac{3}{4}\) + \(x\) \(\times\) \(\dfrac{1}{4}\) = \(\dfrac{7}{8}\)

    \(x\) \(\times\) ( \(\dfrac{3}{4}\) + \(\dfrac{1}{4}\)) = \(\dfrac{7}{8}\)

   \(x\)   \(\times\) 1 = \(\dfrac{7}{8}\)

   \(x\)     = \(\dfrac{7}{8}\)

d, \(x\times\) \(\dfrac{3}{4}\) - \(x\) \(\times\) \(\dfrac{1}{4}\) = \(\dfrac{7}{8}\)

    \(x\) \(\times\) ( \(\dfrac{3}{4}\) - \(\dfrac{1}{4}\)) = \(\dfrac{7}{8}\)

    \(x\) \(\times\) \(\dfrac{1}{2}\)  = \(\dfrac{7}{8}\)

   \(x\)           = \(\dfrac{7}{8}\) : \(\dfrac{1}{2}\)

   \(x\)          = \(\dfrac{7}{4}\)

3:

a: 3^x*3=243

=>3^x=81

=>x=4

b; 2^x*16^2=1024

=>2^x=4

=>x=2

c: 64*4^x=16^8

=>4^x=4^16/4^3=4^13

=>x=13

d: 2^x=16

=>2^x=2^4

=>x=4

a: =>x=3/7+3/5=15/35+21/35=36/35

b: =>x/35=4/5-5/7=28/35-25/35=3/35

=>x=3

c: =>x<3/4+8/4=11/4

=>\(x\in\left\{0;1;2;3\right\}\)

d: =>5/3<x<5/6+24/6=29/6

=>\(x\in\left\{2;3;4\right\}\)

e: =>x<10/12-9/12=1/12

=>x=0

f: =>2/3<x<12/6-5/6=7/6

=>x=1

1: x=3/4-1/2=3/4-2/4=1/4

2: x-1/5=2/11

=>x=2/11+1/5=21/55

3: x-5/6=16/42-8/56

=>x-5/6=8/21-4/28=5/21

=>x=5/21+5/6=15/14

4: x/5=5/6-19/30

=>x/5=25/30-19/30=6/30=1/5

=>x=1

5: =>|x|=1/3+1/4=7/12

=>x=7/12 hoặc x=-7/12

6: x=-1/2+3/4

=>x=3/4-1/2=1/4

11: x-(-6/12)=9/48

=>x+1/2=3/16

=>x=3/16-1/2=-5/16

1)x= 1/4

2)x= 2/11+ 1/5

   x= 21/55

3)x - 5/6 = 5/21

   x         = 5/21+5/6

   x         = 15/14

4)x/5 = 5/6 + -19/30

   x:5 = 1/5

   x    = 1/5.5

   x    = 1

5) |x| - 1/4 = 6/18

    |x|           = 6/18 - 1/4

    |x|            =7/12

⇒x= 7/12 hoặc -7/12

6)x = -1/2 +3/4

   x= 1/4

7) x/15 = 3/5 + -2/3

   x:15  = -1/15

  x        = -1/15. 15

  x        = -1

8)11/8 + 13/6 = 85/x  

       85/24      = 85/x

  ⇒      x           = 24

9) x - 7/8 = 13/12

   x          = 13/12 + 7/8

   x          = 47/24

10)x - -6/15 = 4/27  

     x            = 4/27 + (-6/15)

    x             = -34/135

11) -(-6/12)+x = 9/48

                    x= 9/48 - 6/12

                    x = -5/16

12) x - 4/6 = 5/25 + -7/15

      x -4/6  =  -4/15

     x           = -4/15 + 4/6

    x             = 2/5

\(\dfrac{x-1}{7}+\dfrac{x-2}{3}+\dfrac{x-3}{5}+\dfrac{x-4}{2}=6\\ =>\left(\dfrac{x-1}{7}-1\right)+\left(\dfrac{x-2}{3}-2\right)+\left(\dfrac{x-3}{5}-1\right)+\left(\dfrac{x-4}{2}-2\right)=0\\ =>\dfrac{x-8}{7}+\dfrac{x-8}{3}+\dfrac{x-8}{5}+\dfrac{x-8}{2}=0\\ =>\left(x-8\right)\left(\dfrac{1}{7}+\dfrac{1}{3}+\dfrac{1}{5}+\dfrac{1}{2}\right)=0\\ =>x-8=0\\ =>x=8\)

chắc ko bro :)?

a) Ta có: \(\dfrac{x-1}{-4}=\dfrac{-4}{x-1}\)

\(\Leftrightarrow\left(x-1\right)^2=16\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=4\\x-1=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)

Vậy: \(x\in\left\{5;-3\right\}\)

b) Ta có: \(\dfrac{x-4}{6}=\dfrac{-1}{3}\)

\(\Leftrightarrow x-4=-2\)

hay x=2

Vậy: x=2

a/ 

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

\(x+\dfrac{1}{4}+\dfrac{4}{x-1}=0\)

\(\dfrac{x\left(x-1\right)4}{4\left(x-1\right)}+\dfrac{16}{4\left(x-1\right)}=0\)

\(4x\left(x-1\right)+16=0\)(quy tắc khử mẫu lớp 8)

\(4x^2-4x+16=0\)

\(4x^2-2x-2x+16=0\)

\(\left(4x^2-2x\right)-\left(2x-16\right)=0\)

\(2x\left(2x-1\right)-2\left(x-16\right)=0\)

a) \(6.8^{x-1}+8^{x+1}=6.8^{19}+8^{21}\)

\(\Rightarrow x-1+x+1=19+21\)

\(=2x=40\)

\(\Rightarrow x=20\)

b) \(4.3^{x-1}+2.3^{x+2}=4.3^6+2.3^9\)

\(\Rightarrow x-1+x+2=6+9\)

\(\Rightarrow2x+1=15\)

\(\Rightarrow2x=14\)

\(\Rightarrow x=7\)