Question

(1,5 điểm) Tìm $x$, biết:

a) $x+\dfrac{2}{5}=\dfrac{-4}{3}$;

b) $\dfrac{-5}{6}+\dfrac{1}{3} . x=\Big(\dfrac{-1}{2}\Big)^2$;

c) $\dfrac{7}{12}-\Big(x+\dfrac{7}{6}\Big) . \dfrac{6}{5}=\Big(\dfrac{-1}{2}\Big)^3$.

Answer 1

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 2

\(a,x+\dfrac{2}{5}=-\dfrac{4}{3}\\ \Rightarrow x=-\dfrac{26}{15}\\ b,-\dfrac{5}{6}+\dfrac{1}{3}x=\left(-\dfrac{1}{2}\right)^2\\ \Rightarrow-\dfrac{5}{6}+\dfrac{1}{3}x=\dfrac{1}{4}\\ \Rightarrow\dfrac{1}{3}x=\dfrac{13}{12}\\ \Rightarrow x=\dfrac{13}{4}\\ c,\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\left(-\dfrac{1}{2}\right)^3\\ \Rightarrow\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=-\dfrac{1}{8}\\ \Rightarrow\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{17}{24}\\ \Rightarrow x+\dfrac{7}{6}=\dfrac{85}{144}\\ \Rightarrow x=-\dfrac{83}{144}.\)

Answer 3

a) x= -26/15

b) x= 17/12

c) x= -1/3

Answer 4

sger

Answer 5

a)x= -2

b) 13/36

c) -83/144

Answer 6

a)\(x+\dfrac{2}{5}=\dfrac{-4}{3}\)

\(x=\dfrac{-4}{3}-\dfrac{2}{5}\)

\(x=\dfrac{-26}{15}\)

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

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

\(\dfrac{1}{3}.x=\dfrac{13}{12}\)

\(x=\dfrac{13}{4}\)

c)\(\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\left(-\dfrac{1}{2}\right)^3\)

\(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{7}{12}+\left(-\dfrac{1}{8}\right)\)

\(x.\dfrac{6}{5}+\dfrac{7}{6}.\dfrac{6}{5}=\dfrac{11}{24}\)

\(x.\dfrac{6}{5}+\dfrac{7}{5}=\dfrac{11}{24}\)

\(x.\dfrac{6}{5}=\dfrac{11}{24}-\dfrac{7}{5}\)

\(x.\dfrac{6}{5}=-\dfrac{24}{25}\)

\(x=\dfrac{-24}{25}:\dfrac{6}{5}=\dfrac{-24}{25}.\dfrac{5}{6}=\dfrac{-14}{15}\)

Answer 7

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 8

a/-26/15

b/13/4

c/-83/144

 

 

Answer 9

 

Answer 10

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 11

a. x+2/5=-4/3

    x=-4/3-2/5

    x=-26/15

  vậy x= -26/15

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

     -5/6+ 1/3  .x= 1/4

               1/3 .x =1/4 -(-5/6)

                1/3 .x = 13/12

                       x=13/12:1/3

                        x= 13/4

      vậy x = 13/4

 c, 7/12-(x+7/6) .6/5 =(-1/2)3

      7/12 -(x+7/6) . 6/5 =-1/8

      (x + 7/6) .6/5 = 11/24

      x+7/6  = 11/24 . 6/5 

  x+7/6 =11/20

    x=11/20-7/6

     x= -37/60 

    vậy x = -37/60

Answer 12

a)x+2/5=-4/3

×=-4/3-2/5

×=-4/3+-2/5=-20/15+-6/15=-26/15

b)-5/6+1/3×x=(-1/2)^2

-5/6+1/3×x=1/4

1/3×x=1/4+5/6

1/3×x=3/12+10/12

1/3×x=13/12

x=13/12÷1/3

x=13/12×3/1=13/4

c)7/12-(x+7/6)×6/5=(-1/2)^3

7/12-(x+7/6)×6/5=-1/8

(x+7/6)×6/5=7/12-(-1/8)

(x+7/6)×6/5=17/24

x+7/6=17/24÷6/5

x+7/6=85/144

x=85/144-7/6

×=85/144-168/144

x=85/144+-168/144=-83/144

 

Answer 13

a) x+\(\dfrac{2}{5}=\dfrac{-4}{3}\)

           x=\(\dfrac{-4}{3}-\dfrac{2}{5}\)

           x=\(\dfrac{-20}{15}-\dfrac{6}{15}\)

           x=\(\dfrac{-26}{15}\)

Vậy, x=\(\dfrac{-26}{15}\)

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

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

               \(\dfrac{1}{3}.x=\dfrac{1}{4}-\dfrac{-5}{6}\)

               \(\dfrac{1}{3}.x=\dfrac{3}{12}+\dfrac{10}{12}\)

               \(\dfrac{1}{3}.x=\dfrac{13}{12}\)

                    \(x=\dfrac{13}{12}:\dfrac{1}{3}\)

                    \(x=\dfrac{13}{12}.3\)

                    x  = \(\dfrac{13}{4}\)

Vậy, x=\(\dfrac{13}{4}\)

c)\(\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\)\(\left(\dfrac{-1}{2}\right)^3\)

    \(\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{-1}{8}\)

              \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{7}{12}-\dfrac{-1}{8}\)

              \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{7}{12}+\dfrac{1}{8}\)

              \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{14}{24}+\dfrac{3}{24}\)

              \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{17}{24}\)

                         \(x+\dfrac{7}{6}=\dfrac{17}{24}:\dfrac{6}{5}\)

                            x+\(\dfrac{7}{6}=\dfrac{17}{24}.\dfrac{5}{6}\)

                            x+\(\dfrac{7}{6}=\dfrac{85}{144}\)

                                  x =\(\dfrac{85}{144}-\dfrac{7}{6}\)

                                  x =\(\dfrac{-83}{144}\)

   

.

Answer 14

a) x + 2/5 = - 4/3   x = - 4/3 - 2/5   x= -26/15

b) -5/6 + 1/3 . x = (-1/2)*2   -5/6 + 1/3 . x = 1/4   1/3 . x = 1/4 - (-5/6)= 13/12   x= 13/12 : 1/3  x= 13/4

c) 7/12 - ( x + 7/6 ) . 6/5 = (-1/2)*3   7/12 - ( x + 7/6 ) . 6/5 = -1/8   ( x + 7/6 ). 6/5 = 7/12 - (-1/8) = 17/24 

x + 7/6 = 11/24 : 6/5= 85/144  x = 85/144 - 7/6  x= -83/144

Answer 15

a x + 2/5 = -4/3

   x          = (-4/3) - 2/5

   x          = -26/15

Vậy x = -26/15

b -5/6 +1/3 .x = (-1/2)²

    -5/6 +1/3 .x = 1/4

             1/3 .x =1/4 + 5/6 

              1/3 . x = 13/12 

                     x   = 13/12 : 1/3

                     x = 13/4

Vậy x = 13/4 

c 7/12 - ( x +7/6 ).6/5 = (-1/3)³

    ^{7/12 - ( x + 7/6) .6/5 =-1/8}

              ^{(x + 7/6) .6/5 = 7/12 - (-1/8)}

               ^{(x + 7/6) .6/5 = 17/24}

                ^{x+7/6        = 17/24 : 6/5} 

                 ^{x+7/6       = 85/144}

                ^{x               = 85/144 - 7/6} 

                ^{x               = -83/144}

Vậy x = -83 / 144

 

 

Answer 16

a) x+2/5=-4/3

x=-4/3-2/5

x=-26/15

b) -5/6+1/3.x = (-1/2)^2

-5/6+1/3.x=1/4

1/3.x=1/4+5/6

1/3.x=13/12

x=13/12:1/3

x=13/4

c) 7/12-(x+7/6).6/5=(-1/2)^3

7/12-(x+7/6).6/5=-1/8

(x+7/6).6/5=7/12-(-1/8)

(x+7/6).6/5=17/24

x+7/6=85/144

x=85/144-7/6

x=-83/144

Answer 17

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Answer 18

a)x+2/5=-4/3

x=-4/3-2/5

x=-26/15

b)-5/6+1/3.x=(-1/2)²

-5/6+1/3.x=1/4

1/3.x=1/4+5/6

1/3.x=13/12

x=13/12:1/3

x=13/4

c)7/12-(x+7/6).6/5=(-1/3)³

7/12-(x+7/6).6/5=-1/8

(x+7/6).6/5=7/12-(-1/8)

(x+7/6).6/5=17/24

x+7/6=85/144

x=85/144-7/6

x=-83/144

 

Answer 19

a) \(x+\dfrac{2}{5}=\dfrac{-4}{3}\)

\(x=\dfrac{-4}{3}-\dfrac{2}{5}\)

\(x=\dfrac{-26}{15}\)

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

\(\dfrac{-5}{6}+\dfrac{1}{3}.x=\dfrac{1}{4}\)

\(\dfrac{1}{3}.x=\dfrac{1}{4}-\dfrac{-5}{6}\)

\(\dfrac{1}{3}.x=\dfrac{13}{12}\)

\(x=\dfrac{13}{12}:\dfrac{1}{3}\)

\(x=\dfrac{13}{4}\)

c) \(\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\left(\dfrac{-1}{2}\right)^3\)

     \(\dfrac{7}{12}-\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{-1}{8}\)

                \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{7}{12}-\dfrac{-1}{8}\)

                \(\left(x+\dfrac{7}{6}\right).\dfrac{6}{5}=\dfrac{17}{24}\)

                           \(x+\dfrac{7}{6}=\dfrac{17}{24}:\dfrac{6}{5}\)

                           \(x+\dfrac{7}{6}=\dfrac{85}{144}\)

                                   \(x=\dfrac{85}{144}-\dfrac{7}{6}\)

                                   \(x=\dfrac{-83}{144}\)

Answer 20

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 21

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 22

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 23

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 24

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 25

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 26

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 27

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 28

a) x + 2/5 = -4/3

x = -4/3 - 2/5

x = -26/15

b) -5/6 + 1/3 x = (-1/2)²

-5/6 + 1/3 x = 1/4

1/3 x = 1/4 + 5/6

1/3 x = 13/12

x = 13/12 : 1/3

x = 13/4

c) 7/12 - (x + 7/6) . 6/5 = (-1/2)³

7/12 - (x + 7/6) . 6/5 = -1/8

(x + 7/6) . 6/5 = 7/12 + 1/8

(x + 7/6) . 6/5 = 17/24

x + 7/6 = 17/24 : 6/5

x + 7/6 = 85/144

x = 85/144 - 7/6

x = -83/144

Answer 29

a)X + 2/5 =-4/3
x          = -4/3 -2/5
x          = 26/15
b)-5/6 +1/3 x X = (-1/2)3=-1/8
             1/3 x X = -1/8 - (-5/6) = 17/24
                      X = 17/24 : 1/3
                     X = 17/8
c)7/12 - (X + 7/6) x 6/5 = (-1/2)3 = -1/8
              (X+7/6) x 6/5 = -1/8 + 7/12 = 11/24
              X + 7/6          = 11/24 : 6/5 = 55/144
              X                    = 55/144 - 7/6
              X                     = -113/144

 

Answer 30

a) x + 2/5 =-4/3

x               =-4/3-2/5

x               =-20/15-6/15

x               =-26/15

b)-5/6+1/3.x=(-1/2)²

-5/6+1/3.x=1/4

1/3.x           =5/6+1/4

1/3.x           =20/24+6/24

1/3.x           =26/24=13/12

x                 =13/12: 1/3

x                 =13/14 ( 12,3 rút rọn cho 3 )

c) 7/12-(x+7/6).6/5=(-1/2)³

7/12-(x+7/6).6/5=(-1/8)

 

(x+7/6).6/5=7/12-(-1/8)

(x+7/6).6/5=7/12+1/8

(x+7/6).6/5=14/24+3/24

(x+7/6).6/5=17/24

x+7/6        =17/24:6/5

x+7/6        =17/24.5/6

x+7/6        =85/144

x               =85/144-7/6

x               =85/144-168/144

x               =-83/144