Question

Tìm x, biết :
a) $\dfrac{1}{2}-\left(x+\dfrac{1}{3}\right)=\dfrac{5}{6}$
b) $\left(\dfrac{3}{8}-\dfrac{1}{5}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}$

Answer 1

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

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{1}{2}-\dfrac{5}{6}\)

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{3}{6}-\dfrac{5}{6}\)

\(\Rightarrow x+\dfrac{1}{3}=-\dfrac{2}{6}\)

\(\Rightarrow x=-\dfrac{2}{6}-\dfrac{1}{3}\)

\(\Rightarrow x=-\dfrac{2}{3}\)

b) \(\left(\dfrac{3}{8}-\dfrac{1}{5}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\)

\(\Rightarrow\left(\dfrac{15}{40}-\dfrac{8}{40}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\)

\(\Rightarrow\dfrac{7}{40}+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\)

\(\Rightarrow\dfrac{5}{8}-x=\dfrac{1}{5}-\dfrac{7}{40}\)

\(\Rightarrow\dfrac{5}{8}-x=\dfrac{1}{40}\)

\(\Rightarrow x=\dfrac{5}{8}-\dfrac{1}{40}\)

\(\Rightarrow x=\dfrac{3}{5}\)

Answer 2

x+13=12−56x+13=12−56

x=−13−13x=−13−13

x=−23x=−23;
b) 

Answer 3

a) x= -2/3

b) x=3/5

Answer 4

.

Answer 5

a) x+\dfrac{1}{3}=\dfrac{1}{2}-\dfrac{5}{6}x+31​=21​−65​

x=-\dfrac{1}{3}-\dfrac{1}{3}x=−31​−31​

x=-\dfrac{2}{3}x=−32​;
b) \dfrac{3}{8}+\dfrac{5}{8}-\dfrac{1}{5}-x=\dfrac{1}{5}83​+85​−51​−x=51​

x=1-\dfrac{1}{5}-\dfrac{1}{5}x=1−51​−51​

x=\dfrac{3}{5}x=53​.

Answer 6

a)x+1/3=1/2-5/6

  x=-2/3

Vậy x = -2/3

b) 3/8+5/8-1/5-x=1/5

x=1-1/5-1/5

x=3/5

Vậy x=3/5

 

Answer 7

a) x+\dfrac{1}{3}=\dfrac{1}{2}-\dfrac{5}{6}x+31​=21​−65​

x=-\dfrac{1}{3}-\dfrac{1}{3}x=−31​−31​

x=-\dfrac{2}{3}x=−32​;
b) \dfrac{3}{8}+\dfrac{5}{8}-\dfrac{1}{5}-x=\dfrac{1}{5}83​+85​−51​−x=51​

x=1-\dfrac{1}{5}-\dfrac{1}{5}x=1−51​−51​

x=\dfrac{3}{5}x=53​.

Answer 8

Answer 9

A ,x = -2/3
B x = 3/5

Answer 10

Answer 11

a, 1/2 - (x + 1/3 ) = 5/6                                                                                            b, (3/8 - 1/5) + ( 5/8 - x ) = 1/5 

     x +1/3 = 1/2 - 5/6                                                                                                    3/8 - 1/5 + 5/8 -x = 1/5 

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

                                                                                                                                      x = 3/5                                      

Answer 12

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

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

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

              \(x=\dfrac{-2}{3}\)

vậy  \(x=\dfrac{-2}{3}\)

b) \(\left(\dfrac{3}{8}-\dfrac{1}{5}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\)

        \(\dfrac{3}{8}+\dfrac{5}{8}-\dfrac{1}{5}-x=\dfrac{1}{5}\)         

                              \(x=1-\dfrac{1}{5}-\dfrac{1}{5}\)     

                             \(x=\dfrac{3}{5}\)           

vậy \(x=\dfrac{3}{5}\)

                                                           

Answer 13

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

\(\dfrac{1}{2}\) - x - \(\dfrac{1}{3}\) = \(\dfrac{5}{6}\)

\(\dfrac{1}{6}\) - x = \(\dfrac{5}{6}\)

- x = \(\dfrac{5}{6}\) - \(\dfrac{1}{6}\)

- x = \(\dfrac{2}{3}\)

x = -\(\dfrac{2}{3}\)

b, ( \(\dfrac{3}{8}-\dfrac{1}{5}\) ) + \(\left(\dfrac{5}{8}-x\right)\) = \(\dfrac{1}{5}\)

\(\dfrac{7}{40}\) + \(\left(\dfrac{5}{8}-x\right)\) = \(\dfrac{1}{5}\)

\(\dfrac{4}{5}-x=\dfrac{1}{5}\)

- x = \(\dfrac{1}{5}-\dfrac{4}{5}\)

- x = -\(\dfrac{3}{5}\)

x = -(-\(\dfrac{3}{5}\))

x = \(\dfrac{3}{5}\)

Answer 14

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

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

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

\(x=-\dfrac{2}{3}\)

\(b,(\dfrac{3}{8}-\dfrac{1}{5})+(\dfrac{5}{8}-x)=\dfrac{1}{5}\)

\(x=1-\dfrac{1}{5}-\dfrac{1}{5}\)

\(x=\dfrac{3}{5}\)

 

Answer 15

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

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

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

               \(x=-\dfrac{2}{3}\)  

b) \(\left(\dfrac{3}{8}-\dfrac{1}{5}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\) 

               \(\dfrac{3}{8}+\dfrac{5}{8}-\dfrac{1}{5}-x=\dfrac{1}{5}\)

                                      \(x=1-\dfrac{1}{5}-\dfrac{1}{5}\)

                                      \(x=\dfrac{3}{5}\) 

Answer 16

x+13=12−56x+13=12−56

x=−13−13x=−13−13

x=−23x=−23

b) 

38+58−15−x=1538+58−15−x=15

x=1−15−15x=1−15−15

x=35x=35

Answer 17

               

Answer 18

a) 1/2 - ( x + 1/3 ) = 5/6

x +1/3 = 1/2 - 5/6

x + 1/3 = -1/3

x = -1/3 - 1/3

x = -2/3

Vậy x = -2/3

b) ( 3/8 - 1/5 ) + ( 5/8 - x ) = 1/5

7/40 + ( 5/8 - x ) = 1/5

5/8 - x = 1/5 - 7/40

5/8 - x = 1/40

x = 5/8 - 1/40

x = 3/5

Vậy x = 3/5

Answer 19

Answer 20

    

Answer 21

hmj,

Answer 22

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

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

            \(x+\dfrac{1}{3}=\dfrac{3}{6}-\dfrac{5}{6}\)

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

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

           \(x=\dfrac{-2}{3}\) 

Answer 23

a, x+1/3=1/2-56

x+1/3=-1/3

x=-1/3-1/3

x=-2/3

b,3/8+5/8-1/5-x=1/5

1-1/5-x=1/5

x= 1-1/5-1/5

x=3/5

Answer 24

A, 1/2 - (x + 1/3) = 5/6

1/2 - x - 1/3 = 5/6

1/2 - 1/3 = 5/6 + x

1/6 = 5/6 + x

1/6 - 5/6 = x

-4/6=x

B, (3/8 - 1/5) + (5/8 - x) = 1/5

3/8 - 1/5 + 5/8 - x = 1/5

3/8 - 1/5 + 5/8 = 1/5 + x 

3/8 + 5/8 - 1/5 = 1/5 + x

8/8 - 1/5 = 1/5 + x

1 - 1/5 = 1/5 + x

5/5 - 1/5 = 1/5 + x

4/5 = 1/5 + x

4/5 - 1/5 = x

3/5 = x

Answer 25

a) 12−(�+13)=5621​−(x+31​)=65​

⇒�+13=12−56⇒x+31​=21​−65​

⇒�+13=36−56⇒x+31​=63​−65​

⇒�+13=−26⇒x+31​=−62​

⇒�=−26−13⇒x=−62​−31​

⇒�=−23⇒x=−32​
 

Answer 26

a)x=\(^{\dfrac{-2}{3}}\)

b)x=\(\dfrac{3}{5}\)

Answer 27

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

\(\dfrac{1}{2}-x-\dfrac{1}{3}=\dfrac{5}{6}\)

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

\(x=-\dfrac{2}{3}\)

b)\(\left(\dfrac{3}{8}-\dfrac{1}{5}\right)+\left(\dfrac{5}{8}-x\right)=\dfrac{1}{5}\)

\(\dfrac{3}{8}-\dfrac{1}{5}+\dfrac{5}{8}-x=\dfrac{1}{5}\)

\(\dfrac{4}{5}-x=\dfrac{1}{5}\)

\(x=\dfrac{3}{5}\)

Answer 28

a) -(x + 1/3) = 5/6 - 1/2                             b) ( 7/40) + ( 5/8-x) = 1/5
    -(x + 1/3) = 1/3                                          7/10 + ( -x=5/8)= 1/5
    ( x + 1/3) = -1/3                                              -x+ 5/8= 1/5 - 7/10
                 x=  -1/3 - 1/3                                      -x+ 5/8= 2/10- 7/10
                  x= -2/3                                                -x+ 5/8= -5/10
                                                                             -x+ 5/8= -1/2
                                                                              -x= -1/2 - 5/8
                                                                              -x= -8/16 - 10/16
                                                                               -x= -18/16

                                                                                -x= -9/8
                                                                                 -x= 9/8

Answer 29

a/

x = -1/3- 1/3

x = -2/3

b/

x = 1 - 1/5 - 1/5

x = 3/5

 

Answer 30

xzdan bngh