Ta có:

\(60\%X+\dfrac{2}{3}=\dfrac{1}{3}.6+\dfrac{1}{3}\\ < =>60\%X=\dfrac{1}{3}.6+\dfrac{1}{3}-\dfrac{2}{3}\\ < =>60\%X=2+\dfrac{1}{3}-\dfrac{2}{3}\\ < =>60\%X=\dfrac{5}{3}\\ =>X=\dfrac{5}{3}:60\%=\dfrac{25}{9}\)

Vậy: X có giá trị bằng 25/9

a) \(60\%x+\frac{2}{3}x=\frac{1}{3}.6\frac{1}{3}\)

=> \(\frac{3}{5}x+\frac{2}{3}x=\frac{19}{9}\)

=> \(\frac{19}{15}x=\frac{19}{9}\)

=> \(x=\frac{19}{9}:\frac{19}{15}\)

=> \(x=\frac{5}{3}\)

b) (-0,6x - 1/3) . 3/5 - (-1) = 1/3

=> (-3/5x - 1/3) .3/5 = 1/3 - 1

=> (-3/5x - 1/3).3/5 = -2/3

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

=> -3/5x - 1/3 = -10/9

=> -3/5x = -10/9 + 1/3

=> -3/5x = -7/9

=> x = -7/9 : (-3/5)

=>  x = 35/27

a,60%x+2/3x=1/3.6 1/3

   x(60%+2/3)=19/6

   x.19/15=19/6

  x=19/6 : 19/15

  x=5/2                

b,[-0,6x-1/2].3/4-(-1)=1/3

   (-3/5x-1/2).3/4=1/3-1

    (-3/5x-1/2).3/4=-2/3

     -0,6x-0,5=-2/3:3/4

      ................................

c,2[1/2x-1/3]-3/2=1/4    

.......................................         (tương tự...)         

 d,Số đó là:720% : 2/3=10,8

c) 2(1/2x - 1/3) - 3/2 = 1/4

=> 2(1/2x - 1/3) = 1/4 + 3/2

=> 2(1/2x - 1/3) = 7/4

=> 1/2x - 1/3 = 7/4 : 2

=> 1/2x - 1/3 = 7/8

=> 1/2x = 7/8 + 1/3

=> 1/2x = 29/24

=> x = 29/24 : 1/2

=> x = 29/12

d) Số đó là : 720% : 2/3 = 54/5

Bài 2: 

a: (x+3)/5=5/7

=>x+3=25/7

hay x=4/7

b: ||x-5|-4|=5

=>|x-5|-4=5 hoặc |x-5|-4=-5

=>|x-5|=9

=>x-5=9 hoặc x-5=-9

=>x=14 hoặc x=-4

c: \(\left(-\dfrac{4}{3}\right)^{3x+1}=\dfrac{256}{81}\)

nên 3x+1=4

=>3x=3

hay x=1

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

\(\Leftrightarrow-5x-\frac{1}{5}-\frac{1}{2}x+\frac{1}{3}=\frac{3}{2}x-\frac{5}{6}\)

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

\(\Leftrightarrow\left(\frac{-10}{2}x-\frac{1}{2}x\right)+\left(\frac{5}{15}-\frac{3}{15}\right)=\frac{3}{2}x-\frac{5}{6}\)

\(\Leftrightarrow\frac{-11}{2}x+\frac{2}{15}=\frac{3}{2}x-\frac{5}{6}\)

\(\Leftrightarrow\frac{-11}{2}x-\frac{3}{2}x=-\frac{5}{6}-\frac{2}{15}\)

\(\Leftrightarrow\frac{-14}{2}x=-\frac{25}{30}-\frac{4}{30}\)

\(\Leftrightarrow-7x=-\frac{29}{30}\)

\(\Leftrightarrow x=-\frac{29}{30}\times\frac{-1}{7}\)

\(\Leftrightarrow x=\frac{29}{210}\)

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

\(\Leftrightarrow3x-\frac{3}{2}-5x-3=\frac{1}{5}-x\)

\(\Leftrightarrow\left(3x-5x\right)-\left(\frac{3}{2}+3\right)=\frac{1}{5}-x\)

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

\(\Leftrightarrow-2x-\frac{9}{2}=\frac{1}{5}-x\)

\(\Leftrightarrow-2x+x=\frac{1}{5}+\frac{9}{2}\)

\(\Leftrightarrow-x=\frac{2}{10}+\frac{45}{10}\)

\(\Leftrightarrow-x=\frac{47}{10}\)

\(\Leftrightarrow x=\frac{-47}{10}\)

\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)

\(\Leftrightarrow3\left(3x-\frac{1}{2}\right)^3=0-\frac{1}{9}\)

\(\Leftrightarrow3\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\)

\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\div3\)

\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\times\frac{1}{3}\)

\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{27}\)

\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\left(\frac{-1}{3}\right)^3\)

\(\Leftrightarrow3x-\frac{1}{2}=\frac{-1}{3}\)

\(\Leftrightarrow3x=\frac{-1}{3}+\frac{1}{2}\)

\(\Leftrightarrow3x=\frac{-2}{6}+\frac{3}{6}\)

\(\Leftrightarrow3x=\frac{1}{6}\)

\(\Leftrightarrow x=\frac{1}{6}\div3\)

\(\Leftrightarrow x=\frac{1}{6}\times\frac{1}{3}\)

\(\Leftrightarrow x=\frac{1}{18}\)

Nhiều thế vậy ...!!

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