a)x : 3 - 7 * 2 = 1,56

  x : 3 - 14 = 1,56

  x : 3 = 1,56 + 14

  x : 3 = 15,56

  x = 15,56 * 3

  x = 46,68

b)nếu dấu chấm trên đề là dấu phẩy thì:

  x : 6,4 = 1,248

  x = 1,248 * 6,4

  x = 7,9872

c)(x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) = 40

  x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 40

  (x + x + x + x + x) + (1 + 2 + 3 + 4 + 5) = 40

  5 * x + 15 = 40

  5 * x = 40 - 15

  5 * x = 25

  x = 25 : 5

  x = 5

A) X:3 - 7 * 2 = 1,56

   X:3-14=1,56

   X:3=1,56+14

   X:3=5,56

  X= 5,56* 3 =16,68

B) X : 6 . 4 = 1 ,248

 X = 1,248 :4 *6

X=1,872

C)  ĐỀ DÀI LÀM LUN

 = 5X + (1+2+3+4+5) =40

5X+15 =40

5X= 40-15=25

X= 25:5=5

a: =>4/3x=7/9-4/9=1/3

=>x=1/4

b: =>5/2-x=9/14:(-4/7)=-9/8

=>x=5/2+9/8=29/8

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

=>3x=23/12

hay x=23/36

d: =>-5/6-x=7/12-4/12=3/12=1/4

=>x=-5/6-1/4=-10/12-3/12=-13/12

em moi lop 4 mà

\(d,-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)

\(\Leftrightarrow-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-4}{12}\)

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

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

\(\Leftrightarrow-x=-\dfrac{13}{12}\)

\(\Leftrightarrow x=\dfrac{13}{12}\)

\(c,3x+\dfrac{3}{4}=2\dfrac{2}{3}\)

\(\Leftrightarrow3x+\dfrac{3}{4}=\dfrac{8}{3}\)

\(\Leftrightarrow3x=\dfrac{8}{3}-\dfrac{3}{4}\)

\(\Leftrightarrow3x=\dfrac{23}{12}\)

\(\Leftrightarrow x=\dfrac{23}{12}:3\)

\(\Leftrightarrow x=\dfrac{23}{36}\)

Mọi người ơi, giúp em với ạ

a) \(\left(9^4.8+9^4.5\right):\left(9^2.\left(10-1\right)\right)\)

=\(9^4.13:9^3=13.9=117\)

b) 100-(75-25)=100-50=50

\(a,\left(2^3\cdot9^4+9^3\cdot45\right):\left(9^2\cdot10-9^2\right)\)

\(< =>\left(8\cdot6561+729\cdot45\right):\left(81\cdot10-81\right)\)

\(< =>\left(52488+32805\right):\left(810-81\right)\)

\(< =>85293:729\)

\(< =>117\)

\(b,100-\left[75-\left(7-2\right)^2\right]\)

\(< =>100-\left[75-\left(5\right)^2\right]\)

\(< =>100-\left[75-25\right]\)

\(< =>100-50\)

\(< =>50\)

\(c,\left(20\cdot2^4+12\cdot2^4\right)-\left(48\cdot2^2\right):8^2\)

\(< =>\left[2^4\cdot\left(20+12\right)\right]-\cdot\left(48\cdot4\right):8^2\)

\(< =>\left[2^4\cdot32\right]-192:8^2\)

\(< =>\left[16\cdot32\right]-192:64\)

\(< =>512-3\)

\(< =>509\)

a) 1/2x - 2/3x = 7/12

    -1/6x = 7/12

     x = \(\frac{7}{12}\div\frac{-1}{6}\)

     x = -7/2

b)  x: 12 = -2,5

     x = -2,5*12

     x = -30

c) 11/2x = 13/15

    x = 13/15:11/2

    x = 26/165

d) 3x/7 + 1 = (-1/28)*(-4)

    3x/7 + 1 = 1/7

    3x/7 = 1/7 - 1

    3x/7 = -6/7

    3x = -6

    x= -6/3

    x= -2

a) x(0.5 - 2/3 ) = 7/12

        (-1/6)x = 7/12

             x      = 7/12 : (-1/6)

            x      =-7/2

b) x :  12 = -2,5

   x= -2.5 * 12  =-30

c)   x = 13/15 : 5,5

    x  =26/125

d) 3x/7 + 1  =  -1/28 * (-4)

   3x/7 + 1   =1/7

  3x/7    = 1/7 -1

   3x/7  =-6/7

   3x    =-6/7 * 7 

  3x = -6

   x =-2

hsssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss

1)\(25x+3\left(4-6x\right)=50\)

\(25x+12-18x=50\)

\(7x+12=50\)

\(7x=38\)

\(x=\frac{38}{7}\)

2)\(4\left(2x+3\right)+2\left(3x+1\right)=120\)

\(8x+12+6x+2=120\)

\(14x+14=120\)

\(14x=106\)

\(x=\frac{53}{7}\)

3)\(2\left(3x+2\right)+3\left(4x+1\right)=200\)

\(6x+4+12x+3=200\)

\(18x+7=200\)

\(18x=193\)

\(x=\frac{193}{18}\)

1) (-1)³ + (-2)³ + (-3)³ - |x+5| = (5 - 6 -7)³

     (-1) -8 - 27 - |x+5| = -512

                         |x+5| = 476

=> x + 5 = 476 hoặc x + 5 = -476

     =>  x = 472           => x = -481

Vậy....

2) [(x-3)² - 9] . [(x-1)²-1]=0

    ( x - 3 - 3).(x - 3 + 3).(x - 1 - 1).(x - 1 +1) =0

    ( x - 6) . (x - 0) . (x - 2) . (x - 0) = 0

=> x - 6 = 0           hoặc        x - 0 = 0           hoặc x - 2 = 0

     => x = 6                            => x = 0                   => x = 2

Vậy...

3) 2.(x-23) - (x-43) = 96 - 115

     2x - 46 - x + 43 = -19

                           x = -16

\(a,\frac{x+8}{3}+\frac{x+7}{2}=-\frac{x}{5}\)

\(\Leftrightarrow\frac{10\cdot\left(x+8\right)}{30}+\frac{15\left(x+7\right)}{30}=\frac{-6x}{30}\)

\(\rightarrow10x+80+15x+105=-6x\)

\(\Leftrightarrow31x+185=0\)

\(\Leftrightarrow x=-\frac{185}{31}\)

b,\(b,\frac{x-8}{3}+\frac{x-7}{4}=4+\frac{1-x}{5}\)

\(\Leftrightarrow\frac{20\left(x-8\right)}{60}+\frac{15\left(x-7\right)}{60}=\frac{240}{60}+\frac{12\left(1-x\right)}{60}\)

\(\rightarrow20x-160+15x-105=240+12-12x\)

\(\Leftrightarrow47x-517=0\)\(\Leftrightarrow x=11\)

a) => 4/3x = 7/9 - 4/9 = 1/3

=> x = 1/3 : 4/3 = 1/4

b) => 5/2 - x = 9/14 : (-4/7) = -9/8

=> x = 5/2 - (-9/8) = 5/2 + 9/8 = 29/8

c) => 3x = 2 và 2/3 - 3/4 = 8/3 - 3/4 = 23/12

=> x = 23/12 : 3 = 23/36

D) => -5/6 - x = 1/4

=> x = -5/6 - 1/4 = -13/12

a) \(\dfrac{4}{9}+\dfrac{4}{3}x=\dfrac{7}{9}\)

\(\dfrac{4}{3}x=\dfrac{7}{9}-\dfrac{4}{9}=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}:\dfrac{4}{3}\)

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

b) \(\left(\dfrac{5}{2}-x\right)\left(-\dfrac{4}{7}\right)=\dfrac{9}{14}\)

\(\dfrac{5}{2}-x=\dfrac{9}{14}:\left(-\dfrac{4}{7}\right)=-\dfrac{9}{8}\)

\(x=\dfrac{5}{2}-\left(-\dfrac{9}{8}\right)\)

\(x=\dfrac{29}{8}\)

c) \(3x+\dfrac{3}{4}=2\dfrac{2}{3}\)

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

\(3x=\dfrac{8}{3}-\dfrac{3}{4}=\dfrac{23}{12}\)

\(x=\dfrac{23}{12}:3\)

\(x=\dfrac{23}{36}\)

d) \(-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)

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

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

\(x=-\dfrac{13}{12}\)