\(a,5x-16=40-1\)

<=>\(5x=40-1+16\)

<=>\(5x=55\)

<=>\(x=11\)

\(b,x-10=-25\)

<=>\(x=\left(-25\right)-10\)

<=>\(x=-35\)

\(c,-12+x=-30\)

<=>\(x=\left(-30\right)+12\)

<=>\(x=-18\)

a) 5x-16=40-1

5x-16=39

5x=39+16

5x=55

x=55:5

x=11

b)x-10=(-25)

x=(-25)+10

x=(-15)

c) -12+x= -30

           x= -30-(-12)

           x= -30+12

           x= -18

d) 2x +12 = -40+ 6

2x+12=(-34)

2x=(-34)-12

2x=(-46)

x=(-46):2

x=(-23)

e)125:(3x-13)=25

3x-13=125:25

3x-13=5

3x=5+13

3x=18

x=18:3

x=6

f)541+(218-x)=735

218-x=735-541

218-x=194

x=218-194

x=  24

g) 3(2x+1)-19=14

3(2x+1)=14+19

3(2x+1)=33

2x+1=33:3

2x+1=11

2x=11-1

2x=10

x=10:2

x=5

h)175-5(x+3)=85

5(x+3)=175-85

5(x+3)=90

x+3=90:5

x+3=18

x=18-3

x=15

i)8x+(-3)=39

8x=39-(-3)

8x=42

x=42:8

x=42/8

L)2x+4x=36+(-6)

6x=30

x=30:6

x=5

a ) 126 - 2x = 12 - ( -28 )

     126 - 2x = 40

     2x = 126 - 40

     2x = 86 

     x = 86 : 2

     x = 43

b ) 25 - 5( x + 1 ) = 30 - 125

     25 - ( 5x + 5 ) = -95

     25 - 5x - 5 = -95

     20 - 5x = -95

     5x = 20 - ( - 95 )

     5x = 115

     x = 115 : 5

     x = 23

c ) I 3x - 1 I - 25 = 73 

     I 3x - 1 I = 73 + 25

     I 3x - 1 I = 98

=> 3x - 1 = 98 hoặc 3x - 1 = -98

=> 3x = 98 + 1 hoặc 3x = -98 + 1

=> 3x = 99 hoặc 3x = -97

=> x = 99 : 3 hoặc x = -97 : 3 

=> x = 33 hoặc x = -93/3

d ) 2( x + 2 ) - 6 = 120 - 4x 

     2x + 4 - 6 = 120 - 4x 

     2x - 2 = 120 - 4x

     2x + 4x = 120 + 2

     6x = 122

     x = 122 : 6

     x = 61/3

a) x = 43

b) x = 23

c) x = 33 hoac x= -97/3

a) x = 160

b) x = 5

c) x = 107

d) x = 3

a) \(5\left(x-7\right)=0\)

\(\Rightarrow x-7=0\)

\(\Rightarrow x=7\)

b) \(25\left(x-4\right)=0\)

\(\Rightarrow x-4=0\)

\(\Rightarrow x=4\)

c) \(\left(34-2x\right)\left(2x-6\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}34-2x=0\\2x-6=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}2x=34\\2x=6\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=17\\x=3\end{matrix}\right.\)

d) \(\left(2019-x\right)\left(3x-12\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}2019-x=0\\3x-12=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2019\\3x=12\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2019\\x=\dfrac{12}{3}=4\end{matrix}\right.\)

e) \(57\left(9x-27\right)=0\)

\(\Rightarrow9x-27=0\)

\(\Rightarrow9\left(x-3\right)=0\)

\(\Rightarrow x-3=0\)

\(\Rightarrow x=3\)

a) 5.(x-7)=0⇔x-7=0⇔x=7

b) 25(x-4)=0⇔x-4=0⇔x=4

c) (34-2x).(2x-6)=0

⇔ 34-2x=0 hoặc 2x-6=0

⇔2x=34 hoặc 2x=6

⇔ x=17 hoặc x=3

d) (2019-x).(3x-12)=0

⇔ 2019-x=0 hoặc 3x-12=0

⇔ x=2019 hoặc x=4

e) 57.(9x-27)=0

⇔ 9x-27=0

⇔ x=3

f) 25+(15-x)=30

⇔ 15-x=5

⇔ x=10

g) 43-(24-x)=20

⇔ 24-x=23

⇔ x=1

h) 2.(x-5)-17=25

⇔ 2(x-5)=42

⇔x-5=21

⇔ x=26

i) 3(x+7)-15=27

⇔ 3(x+7)=42

⇔ x+7=14

⇔ x=7

j) 15+4(x-2)=95

⇔ 4(x-2)=80

⇔ x-2=20

⇔ x=22

k) 20-(x+14)=5

⇔ x+14=15

⇔ x=1

l) 14+3(5-x)=27

⇔ 3(5-x)=13

⇔ 5-x=13/3

⇔ x=5-13/3

⇔ x=2/3

A , 3 - ( 17 - x ) = 289 -  ( 36 + 289 )

3 - 17 + x = 0 - 36

-14 + x = -36

x = -36 - ( - 14 ) = -22

B, 25 - ( x + 5 ) = -415 - ( 15 - 415 )

25 - x - 5 = 0 - 15

20 - x = -15

x = 20 - ( - 15 ) = 35

C , 34 + ( 21 - x ) = ( 3747 - 30 ) - 3746

34 + 21 - x = 1 - 30 

55 - x = -29

x = 55 - (-29 ) = 74

D , -2x -  ( x -17 ) = 34 - ( -x + 25 )

- 2x - x + 17 = 34 - 25 + x

- 3x + 17 = 9 + x

- 3x - x = 9 - 17

-4x = -8

x = -8 : ( - 4 )

x = 2

E , 17x + ( -16x - 37 ) = x + 43

17x - 16x -37 = x + 43

x - 37 = x + 43

-37 - 43 = x - x 

- 80 = 0      ( vô lý )

G , ( x + 12 ) . (x - 3 ) = 0

\(\hept{\begin{cases}x+12=0\\x-3=0\end{cases}}\)

\(\hept{\begin{cases}x=-12\\x=3\end{cases}}\)

Bạn dùng tính chất phân phối, giao hoán để làm nhé

A+0   B=2400   c=420

=> 315+2x-125-x=412

      315+2x-125-x=412

    315+2x+(-125)+(-x)=412

 315+(-125)+2x+(-x)=412

   190+2x+(-x)=412

          x=412-190

           x=222

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