a) \(\left(x-35\right)-120=0\)

\(\Rightarrow x-35=120\)

\(\Rightarrow x=120+35\)

\(\Rightarrow x=155\)

b) \(124+\left(118-x\right)=217\)

\(\Rightarrow118-x=93\)

\(\Rightarrow x=25\)

c) \(156-\left(x+61\right)=82\)

\(\Rightarrow x+61=74\)

\(\Rightarrow x=13\)

a) ( x - 35 ) - 120 =0

x - 35 = 0 + 120

x - 35 = 120

x = 120 + 35

x = 155

b) 124 + ( 118 - x ) = 217

118 - x = 217 - 124

118 - x = 93

x = 118 - 93

x = 25

c) 156 - ( x + 61 ) = 82

x + 61 = 156 - 82

x + 61 = 74

x = 74 - 61

x = 13

a) 124 + (118 - x) = 217

118 - x = 217 - 124

118 - x = 93

x = 118 - 93

x = 25

b) 156 - (x + 61) = 82

x + 61 = 156 - 82

x + 61 = 74

x = 74 - 61

x = 13

c) 219 - 7(x + 1) = 100

7(x + 1) = 219 - 100

7(x + 1) = 119

x + 1 = 119 : 7

x + 1 = 17

x = 17 - 1

x = 16

d) (3x - 6).3 = 3⁴

3x - 6 = 3⁴ : 3

3x - 6 = 3³

3x - 6 = 27

3x = 27 + 6

3x = 33

x = 33 : 3

x = 11

e) 231 - (x - 6) = 1339 : 13

231 - (x - 6) = 103

x - 6 = 231 - 103

x - 6 = 128

x = 128 + 6

x = 134

a) 124 + (118 - x) = 217

118 - x = 217 - 124

118 - x = 93

x = 118 - 93

x = 25

b) 156 - (x + 61) = 82

x + 61 = 156 - 82

x + 61 = 74

x = 74 - 61

x = 13

c) 219 - 7(x + 1) = 100

7(x + 1) = 219 - 100

7(x + 1) = 119

x + 1 = 119 : 7

x + 1 = 17

x = 17 - 1

x = 16

d) (3x - 6) . 3 = 3⁴

(3x - 6) . 3 = 81

(3x - 6) = 81 : 3

(3x - 6) = 27

3x = 27 + 6

3x = 33

x = 33 : 3 

x = 11

e) 231 - (x - 6) = 1339 : 13

231 - (x - 6) = 103

(x - 6) = 231 - 103

x - 6 = 128

x = 128 + 6

x = 134

a. (x-35)-120=0

=> x-35 = 0+120

=> x-35 = 120

=> x = 120+35

=> x = 155

b. 156-(x+61)=82

=> x+61=156-82

=> x+61=74

=> x = 74-61

=> x = 13

c. 124+(118-x)=217

=> 118-x=217-124

=> 118-x=93

=> x = 118-93

=> x = 25

Vận dụng điều lưu ý trong phần tóm tắt kiến thức.

a) Nếu (x - 35) - 120 = 0 thì x - 35 = 120. Do đó x = 120 + 35 = 155.

b) Nếu 124 + (118 - x) = 217 thì 118 - x = 217 - 124 hay 118 - x = 93.

Do đó x = 118 - 93 = 25.

c) 156 - (x + 61) = 82 suy ra x + 61 = 156 - 82 hay x + 61 = 74.

Do đó x = 74 - 61 = 13.

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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) 156 - ( x + 61 )+82

    sai đề ( không có kết quả )

c) 10 +2 .x = 4⁵ : 4³

    10 + 2 . x = 4² = 16

             2 . x = 16 -10

             2 . x = 6

                  x = 6 : 2

                  x = 3

d) [(10 - x ).2 +3 ];3 -2=13

     [ ( 10 - x ) . 2 + 3 ] : 3 = 13 + 2

     [ ( 10 - x  ) . 2 + 3 ] : 3 = 15 

      [ ( 10 - x  ) . 2 + 3 ]    = 15 x 3

       [ ( 10 - x  ) . 2 + 3 ]    = 45

         ( 10 - x  ) . 2             = 45 - 3

         ( 10 - x  ) . 2             = 42

           10 - x                      = 42 : 2 

           10 - x                      = 21

                  x                       = 10 - 21

                  x                       = - 11

hok tốt

\(70-5\left(x-3\right)=45\)

\(5\left(x-3\right)=70-45\)

\(5\left(x-3\right)=25\)

\(x-3=\frac{25}{5}=5\)

\(x=5+3\)

\(x=8\)

a) x = 25 - 16

x = 9

b) 2x = 156-82

2x = 74

x = 74 : 2

x = 37

c) 150 : (18-x) = 150-125

150 : (18-x) = 25

18-x = 150 : 25

18-x = 6

x =18-6

x= 12

d) 6.6 :x = 8-4

36 : x = 4

x =36:4

x = 9

e)(99x-x) : 2+1= 50x

Ta có:

50x + (1+3+5+7+9+.....+99)=75.10.10

50x + (99+1).50:2 =7500

50x + 2500=7500

50x=7500-2500

50x=5000

x =5000:50

x = 100

Tim x € N biet :

a / x + 16 = 25

=> x = 25 - 16

=> x = 9

b / 156 - 2x = 82

=> 2x = 156 - 82

=> 2x = 74

=> x = 37

c / 150 -150 : ( 18 - x ) = 125

=> 150 : ( 18 - x ) = 125 -150

=> 150 : ( 18 - x ) = - 25

=> 18 - x = -6

=> x = 18 - ( -6 )

=> x = 24

d / 6² : x = 2³ - 4

=> 36 : x = 8 - 4

=> 36 : x = 4

=> x = 36 : 4

=> x = 9

e / x + 3x + 5x + ................. +99x = 75 × 10²

^=> x + 3x + 5x +....+ 99x = 7500

=> x. ( 1 + 3 + 5 +....+ 99 ) = 7500

Số các số hạng là : ( 99 - 1 ) : 2 + 1 = 50

=> Số cặp là : 50 : 2 = 25

Ta có:

x. ( 1 + 3 + 5 +....+ 99 ) = 7500

=> x. [ ( 1 + 99 ) + ( 2 + 98 ) +.... ] = 7500

=> x. 100 .25 =7500

=> x. 2500 = 7500

=> x = 7500 : 2500

=> x = 3

a)

(x-35)-120=0

=>x-35=0+120

=>x-35=120

=>x=120-35

=>x=85

b)

124+(118-x)=217

=>118-x=217-124

=>118-x=93

=>x=118-93

=>x=25

c) 125-(x+61)=82

=>x+61=125-82

=>x+61=43

=>x= 43-61

=>x= -18

a)

(x-35)-120=0

=>x-35=0+120

=>x-35=120

=>x=120-35

=>x=85

b)

124+(118-x)=217

=>118-x=217-124

=>118-x=93

=>x=118-93

=>x=25

c) 125-(x+61)=82

=>x+61=125-82

=>x+61=43

=>x= 43-61

=>x= -18

a/ \(\left(x-35\right)-120=0\)

\(\Leftrightarrow x-35=0+120\)

\(\Leftrightarrow x-35=120\)

\(\Leftrightarrow x=120+35\)

\(\Leftrightarrow x=155\)

Vậy ...

b/ \(124+\left(188-x\right)=217\)

\(\Leftrightarrow188-x=217-124\)

\(\Leftrightarrow188-x=93\)

\(\Leftrightarrow x=95\)

Vậy ...

b/ \(156-\left(x+61\right)=82\)

\(\Leftrightarrow x+61=74\)

\(\Leftrightarrow x=13\)

Vậy ..