a)  2x-3=-x+6

2x - 3 + x - 6 =0

3x -9 = 0

3x = 9

x = 9 : 3

x= 3

c/ \(\left(-12x-4^3\right).8^3=4.8^4\)

\(\left(-12x-64\right).512=16384\)

\(-12x-64=\dfrac{16384}{512}=32\)

\(-12x=32+64=96\)

\(x=\dfrac{96}{\left(-12\right)}=-8\)

a,   2x-3=-x+6

\(\Leftrightarrow\)2x-3+x-6=0

\(\Leftrightarrow\)3x-9=0

\(\Leftrightarrow\)3x=9

\(\Leftrightarrow\)x=3

a) Ta có: \(2x-3=-x+6\)

\(\Leftrightarrow2x+x=6+3\)

\(\Leftrightarrow3x=9\)

hay x=3

Vậy: x=3

b) Ta có: \(\left|2x-7\right|+2=13\)

\(\Leftrightarrow\left|2x-7\right|=11\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-7=11\\2x-7=-11\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=18\\2x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-2\end{matrix}\right.\)

Vậy: \(x\in\left\{9;-2\right\}\)

c) Ta có: \(\left(-12x-4^3\right)\cdot8^3=4\cdot8^4\)

\(\Leftrightarrow\left(-12x-64\right)=\dfrac{4\cdot8^4}{8^3}=32\)

\(\Leftrightarrow-12x=96\)

hay x=-8

Vậy: x=-8

5 + ( x + 27 ) = 64

a) \(\Rightarrow x+27=59\Rightarrow x=32\)

b) \(\Rightarrow x-2=39\Rightarrow x=41\)

c) \(\Rightarrow x+5=-322\Rightarrow x=-327\)

d) \(\Rightarrow5x=35\Rightarrow x=7\)

e) \(\Rightarrow4\left(x-5\right)=56\Rightarrow x-5=14\Rightarrow x=19\)

f) \(\Rightarrow15+x=37\Rightarrow x=22\)

g) \(\Rightarrow7\left(13-x\right)=35\Rightarrow13-x=5\Rightarrow x=8\)

h) \(\Rightarrow10\left(x+1\right)=100\Rightarrow x+1=10\Rightarrow x=9\)

a) x+7=-12

        x=(-12)-7

        x=-19

b)x-15=-21

        x=(-21)+15

        x=-6

c)13-x=20

        x=13-20

        x=-7

d)17-(2+x)=3

      x=17-3

      x=14

      x=14-2

      x=12

a,x+7=-12

=>x= -12-7

=>x= -19

b,x-15= -21

=>x= -21+15

=>x= -6

c,13-x=20

=>x=13-20

=>x= -7

d, 17-(2+x)=3

=>2+x=17-3

=>2+x=14

=>x=14-2

=>x=12

a) \(x+7=-12\) 

    \(x=-12-7\) 

    \(x=-19\) 

b) \(x-15=-21\)  

    \(x=-21+15\) 

    \(x=-6\)  

c) \(13-x=20\) 

            \(x=13-20\)  

            \(x=-7\) 

d) \(17-\left(2+x\right)=3\)  

             \(2+x=17-3\)  

             \(2+x=14\)   

                   \(x=14-2\)  

                   \(x=12\)

` 8/23 . 46/24 =1/3 .x`

`=>8/23 . 23/12 =1/3 . x`

`=> 1/3 . x=2/3`

`=>x=2/3 : 1/3`

`=>x=2/3 . 3`

`=> x= 6/3`

`=>x=2`

`----`

`1/5 : x= 1/5-1/7`

`=>1/5 : x=  7/35 - 5/35`

`=> 1/5 :x= 2/35`

`=>x= 1/5 : 2/35`

`=>x=1/5 . 35/2`

`=>x=7/2`

`----`

`4/9 - (x-1/2)^2 =1/3`

`=> (x-1/2)^2 =4/9-1/3`

`=> (x-1/2)^2 =4/9- 3/9`

`=> (x-1/2)^2 =1/9`

`=> (x-1/2)^2 = (+- 1/3)^2`

`@ TH1`

`x-1/2=1/3`

`=>x=1/3+1/2`

`=>x= 2/6 + 3/6`

``=>x= 5/6`

`@ TH2`

`x-1/2=-1/3`

`=>x=-1/3 +1/2`

`=>x= -2/6 + 3/6`

`=>x=1/6`

`----`

`3,2 . x-(4/5+2/3) : 3 2/3 = 7/10`

`=> 3,2 . x-22/15 : 11/3 = 7/10`

`=>  3,2 . x-22/15 = 7/10 . 11/3`

`=>  3,2 . x-22/15 =77/30`

`=> 3,2 .x= 77/30 + 22/15`

`=> 3,2 .x=121/30`

`=>x= 121/30. 5/16`

`=>x= 121/96`

\(2x^3+x^2-4x-12\)

\(=2x^3+5x^2+6x-4x^2-10x-12\)

\(=\left(2x^3+5x^2+6x\right)-\left(4x^2+10x+12\right)\)

\(=x\left(2x^2+5x+6\right)-2\left(2x^2+5x+6\right)\)

\(=\left(x-2\right)\left(2x^2+5x+6\right)\)

\(a,2x^3+x^2-4x-12=\left(2x^3-4x^2\right)+\left(5x^2-10x\right)+\left(6x-12\right)=2x^2\left(x-2\right)+5x\left(x-2\right)+6\left(x-2\right)=\left(x-2\right)\left(2x^2+5x+6\right)\)

\(b,x^5-xy^4+x^4y-y^5=x\left(x^4-y^4\right)+y\left(x^4-y^4\right)=\left(x+y\right)\left(x^4-y^4\right)=\left(x+y\right)\left(x^2-y^2\right)\left(x^2+y^2\right)=\left(x+y\right)^2\left(x-y\right)\left(x^2+y^2\right)\)

\(c,\left(x+1\right)\left(x+3\right)\left(x+5\right)\left(x+7\right)-9=\left[\left(x+1\right)\left(x+7\right)\right]\left[\left(x+3\right)\left(x+5\right)\right]-9=\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9\)

đặt \(x^2+8x+11=y\)

\(\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9=\left(y-4\right)\left(y+4\right)-9=y^2-16-9=y^2-25=\left(y-5\right)\left(y+5\right)=\left(x^2+8x+11-5\right)\left(x^2+8x+11+5\right)=\left(x^2+8x+6\right)\left(x^2+8x+16\right)=\left(x^2+8x+6\right)\left(x+4\right)^2\)

8/5

686/65

5/7

3/5+7/12+5/12

=3/5+(7/12+5/12)

=3/5+1

=8/5

a.3/5+1=8/5

b.4/26+52/5=686/65

c.(9/16+7/16)*5/7=1*5/7=5/7

a: x*3/4=1/5

=>x=1/5:3/4=1/5*4/3=4/15

b: x*3/7=2/5

=>x=2/5:3/7=2/5*7/3=14/15

c: 1/3+2/9=2/12x

=>1/6x=3/9+2/9=5/9

=>x=5/9*6=30/9=10/3

d: 4/15*x-2/3=1/5

=>4/15*x=2/3+1/5=10/15+3/15=13/15

=>4x=13

=>x=13/4

e: x:1/7=2/3

=>x=2/3*1/7=2/21

f: 1/9:x=7/3

=>x=1/9:7/3=1/9*3/7=3/63=1/21

j: 1/4+5/12=8/3:x

=>8/3:x=3/12+5/12=8/12=2/3

=>x=4

h: =>7/4:x=1/5+1/2=7/10

=>x=7/4:7/10=10/4=5/2

Bài 2:

a) (x+7)-13=25 

  (x+7) - 13 = 25

  (x+7) - 13 + 13 = 25 + 13

  x + 7 = 38

  (x + 7) - 7 = 38 - 7

  x = 31

Vậy, giá trị của x là 31.

b) ( 33-5(x-4)=13 

  33 - 5(x-4) = 13

  33 - 5x + 20 = 13

  -5x + 53 = 13

  -5x = 13 - 53

  -5x = -40

  (-5x)/-5 = (-40)/-5

  x = 8

Vậy, giá trị của x là 8.

C( x+6=3x 

  x + 6 = 3x

  x + 6 - 6 = 3x - 6

  x = 3x - 6

  x - 3x = -6

  (-2x) = -6

  (-2x)/-2 = (-6)/-2

  x = 3

Vậy, giá trị của x là 3.

d) ( 5x+3=2x+12

  5x + 3 = 2x + 12

  5x - 2x = 12 - 3

  3x = 9

  (3x)/3 = 9/3

  x = 3

Vậy, giá trị của x là 3.

`#3107.101107`

1.

a)

`34046 = 30000 + 4000 + 40 + 6`

b)

201012 = 200000 + 1000 + 12`

c)

\(\overline{a2b}=a\times100+20+b\)

d)

\(\overline{abc1}=a\times1000+b\times100+c\times10+1\)

2.

a)

`(x + 7) - 13 = 25`

`=> x + 7 = 25 - 13`

`=> x + 7 = 12`

`=> x = 12 - 7`

`=> x = 5`

Vậy, `x = 5`

b)

`33 - 5(x - 4) = 13`

`=> 5(x - 4) = 33 - 13`

`=> 5(x - 4) = 20`

`=> x - 4 = 20 \div 5`

`=> x - 4 = 4`

`=> x = 4 + 4`

`=> x = 8`

Vậy, `x = 8`

c)

`x + 6 = 3x`

`=> x + 6 - 3x = 0`

`=> (x - 3x) + 6 = 0`

`=> -2x + 6 = 0`

`=> -2x = -6`

`=> 2x = 6`

`=> x = 6 \div 2`

`=> x = 3`

Vậy, `x = 3`

d)

`5x + 3 = 2x + 12`

`=> 5x - 2x = 12 - 3`

`=> 3x = 9`

`=> x = 9 \div 3`

`=> x = 3`

Vậy, `x = 3.`

____

`@` Quy tắc chuyển vế, đổi dấu:

- Khi chuyển vế 1 số hạng vế này qua vế kia, ta đổi dấu cho số hạng đó. Nếu số hạng đó mang dấu dương (+) khi chuyển vế đổi thành dấu âm (-), ngược lại, nếu số hạng đó mang dấu âm (-) khi chuyển vế đối thành dấu dương (+).

\(#V3L6\)