A = 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72

A = 78 x ( 31 + 24 + 17 ) + 22 x 72

A = 78 x 72 + 22 x 72

A = 72 x ( 78 + 22 ) 

A = 72 x 100

A = 7200

C = 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21

C = 39 x ( 53 + 47 ) - 21 x ( 53 - 47 )

C = 39 x 100 - 21 x 6

C = 3900 - 126

C = 3774

ko pc tui thua bn 1 lp 

là biếng viết lời giải

1062

3700

40340

còn lời giải  thích thì hỏi sau

a)997+86=997+3+83=1000+83=1083

b)37.(38+62)=37.100=3700

c)27.332+68.27+73.332+68.78

=27.332+73.332+68.27+68.78

=332.(27+73)+68.(27+78)

=332.100+68.105

=40340

a, 3.(37 - \(x\)) - 56 = 1

   3.(37 - \(x\)) = 1 + 56

   3.(37 - \(x\)) = 57

       37 - \(x\) = 57 : 3

       37 - \(x\) = 19

               \(x\) = 37 - 19

                \(x\) = 18

b, 95 - (2\(x\) - 1).4 = 14

           (2\(x\) - 1).4 = 95 - 14

           (2\(x\) - 1).4 = 81

             2\(x\) - 1 = 81 : 4

             2\(x\)      = \(\dfrac{81}{4}\) - 1

             2\(x\)     = \(\dfrac{85}{4}\)

              \(x\)    = \(\dfrac{85}{4}\) : 2

               \(x\)    = \(\dfrac{85}{8}\)

`@` `\text {Ans}`

`\downarrow`

`a,`

`93,57 \times 19,45 - 93,57 \times 9,45`

`= 93,57 \times (19,45 - 9,45)`

`= 93,57 \times 10`

`= 935,7`

`b,`

`815,5 \times 0,08 + 815,5 \times 0,02`

`= 815,5 \times (0,08 + 0,02)`

`= 815,5 \times 0,1`

`= 81,55`

`c,`

`11 \times 46,79 - 46,79`

`= 46,79 \times (11 - 1)`

`= 46,79 \times 10`

`= 467,9`

`d,`

`92,305 \times 108 - 92,305 \times 8`

`= 92,305 \times (108 - 8)`

`= 92,305 \times 100`

`= 9230,5`

`e,`

`189,28 \times 78 - 189,28 \times 68`

`= 189,28 \times (78 - 68)`

`= 189,28 \times 10`

`= 1892,8`

a) \(93,57\times19,45-93,57\times9,45\)

\(=93,57\times\left(19,45-9,45\right)\)

\(=93,57\times10\)

\(=935,7\)

b) \(815,5\times0,08+815,5\times0,02\)

\(=815,5\times\left(0,08+0,02\right)\)

\(=815,5\times0,1\)

\(=81,55\)

c) \(11\times46,72-46,79\)

\(=46,79\times\left(11-1\right)\)

\(=46,79\times10\)

\(=467,9\)

d) \(92,305\times108-92,305\times8\)

\(=92,305\times\left(108-8\right)\)

\(=92,305\times100\)

\(=9230,5\)

e) \(189,28\times78-189,28\times68\)

\(=189,28\times\left(78-68\right)\)

\(=189,28\times10\)

\(=1892,8\)

a, 512*(2-128)-128*(-512)

   = 512*2 - 512*128 -128*(-512)

   =512*2-512*128-(-128)*512

   = 512*(2-128+128)

   = 512*2

   =1024

   b, 2155-(174+2155)+(-68+174)

     =2155-174-2155+(-68)+174

     = (2155-2155)+[(-174)+174]+(-68)

     =0+0+(-68)

      =-68

    c,-78+11*(97-99)

       =-78+11*(-2)

        =-78+(-22)

       =-100

    d, |+426|+|-345|+|+456|+|-789|

      = 426+345+456+789

      =(426+345)+(456+789)

      =771+1245

      =2016

Câu 1:

25 - x = 37 - 3x

<=> -x + 3x = 37 - 25

<=>    2x     = 12

<=>     x      = 12 : 2

<=>     x      = 6

Câu 2:

68 + x = 75 - 2x

<=> x + 2x = 75 - 68

<=>   3x    = 7

<=>   x      = 7 : 3

<=>   x      = 7/3

Khúc đầu trình bày ko được thẳng hàng sr bạn nhé

Cảm ơn nhiều !!!

Tách ?

`a, 70 -5.(x-3) =45`

`=> 5.(x-3)= 70-45`

`=> 5.(x-3)=25`

`=>x-3=25:5`

`=>x-3=5`

`=>x= 5+3`

`=>x=8`

______

`b,10 + 2.x = 4^5:4^3`

`=> 10 + 2.x = 4^(5-3)`

`=> 10 + 2.x =4^2=16`

`=> 2.x=16-10`

`=>2.x=6`

`=>x=6:2`

`=>x=3`

_____

`c,60-3.x-2=51`

`=>  60-3.x= 51+2`

`=> 60-3.x=53`

`=>3.x=60-53`

`=> 3.x= 7`

`=>x= 7/3`

____

`d, 4.x-20=2^5:2^3`

`=> 4.x-20=2^(5-3)`

`=> 4.x-20=2^2`

`=> 4.x= 4+20`

`=>4.x=24`

`=>x=24:4`

`=>x=6`

____

`2^x . 4=16`

`=> 2^x=16:4`

`=>2^x= 4`

`=>2^x=2^2`

`=>x=2`

____

`f, 3^x . 3=243`

`=>3^x=243:3`

`=> 3^x=81`

`=> 3^x=3^3`

`=>x=3`

_____

`g, 64. 4^x =16^8`

`=> 4^3 . 4^x=(4^2)^8`

`=> 4^3 . 4^x = 4^(16)`

`=> 4^x= 4^(16-3)`

`=>4^x=4^(13)`

`=>x=13`

_____

`2^x . 16^2 =1024`

`=> 2^x= 1024 : 16^2`

`=>2^x=4`

`=>2^x=2^2`

`=>x=2`

a: =>5(x-3)=25

=>x-3=5

=>x=8

b: =>2x=16-10=6

=>x=3

c: =>58-3x=51

=>3x=7

=>x=7/3

d: =>4x-20=4

=>4x=24

=>x=6

e: =>2^x=4

=>2^x=2^2

=>x=2

f: =>3^x=81

=>3^x=3^4

=>x=4

g: =>4^x*4^3=4^16

=>x+3=16

=>x=13

h: =>2^x=1024/256=4=2^2

=>x=2

\(a,\Leftrightarrow x^2\left(x+5\right)-9\left(x+5\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x+3\right)\left(x+5\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=-5\\x=-3\end{matrix}\right.\\ b,\Leftrightarrow\left[{}\begin{matrix}1-2x=3x-2\\2x-1=3x-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\\x=1\end{matrix}\right.\)

a) \(\Leftrightarrow x^2\left(x+5\right)-9x-45=0\)
    \(\Leftrightarrow x^2\left(x+5\right)-9x\left(x+5\right)=0\)
    \(\Leftrightarrow\left(x+5\right)\left(x^2-9\right)=0\)
    \(\Leftrightarrow\left(x+5\right)\left(x-3\right)\left(x+3\right)=0\)
    \(\Leftrightarrow\left[{}\begin{matrix}x+5=0\\x-3=0\\x+3=0\end{matrix}\right.\)
    \(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=3\\x=-3\end{matrix}\right.\)
Vậy...
b) \(\Leftrightarrow\left(1-2x\right)^2-\left(3x-2\right)^2=0\)
    \(\Leftrightarrow\left(1-2x-3x+2\right)\left(1-2x+3x-2\right)=0\)
    \(\Leftrightarrow\left(3-5x\right)\left(x-1\right)=0\)
    \(\Leftrightarrow\left[{}\begin{matrix}3-5x=0\\x-1=0\end{matrix}\right.\)
    \(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\\x=1\end{matrix}\right.\)
Vậy...