4 . 120 + [45 : 9 +15 . (x + 1) = 500

480 + [45 : 9 +15 . (x + 1) = 500

45 : 9 +15 . (x + 1) = 500-480

45 : 9 +15 . (x + 1) = 20

5 +15 . (x + 1) = 20

15 . (x + 1) = 20-5

15 . (x + 1) = 15

x + 1=15:15

x + 1=1

x=1-1

x=0

= 0

tick cho mink nha

4.120+[45:9+15-(x+1)]=500

480+[45:9+15-(x+1)]=500

45:9+15-(x+1)=500-480

45:9+15-(x+1)=20

5+15-(x+1)=20

20-(x+1)=20

x+1=20-20

x+1=0

x=0-1

x=-1

=>4.120+[45:9+15-(x+1)]=500

=>480+[45:9+15-(x+1)]=500

=>45:9+15-(x+1)=500-480

=>45:9+15-(x+1)=20

=>5+15-(x+1)=20

=>20-(x+1)=20

=>x+1=20-20

=>x+1=0

=>x=0-1

=> x=-1

4.120+[45:9+15(x+1)]=500

=>480+[5+15(x+1)]=500

=>5+15(x+1)=20

=>15(x+1)=15

=>x+1=1

=>x=0

4.120+[45:9+15(x+1)]=500

480+[5+15x+15]=500

480+5+15x+15=500

500+15x=500

15x=0

x=0

1) 5x = 120 : 2

5x = 60

x = 60 : 5

x = 12.

2) 3x + 27 = 45

3x = 45 - 27

3x = 18

x = 18 : 3

x = 6.

3) 73 + x - 122 = 234 : 2

73 + x - 122 = 117

73 + x = 117 + 122

73 + x = 239

x = 239 - 73

x = 166.

4) 32 - 2 ( x - 1 ) = 12

2 ( x - 1 ) = 32 - 12

2 ( x - 1 ) = 20

x - 1 = 20 : 2

x - 1 = 10

x = 10 + 1

x = 11.

5) 3 ( x + 1 ) - 15 = 36

3 ( x + 1 ) = 36 + 15

3 ( x + 1 ) = 51

x + 1 = 51 : 3

x + 1 = 17

x = 17 - 1

x = 16.

6) 32 - ( 4x - 16 ) = 21

4x - 16 = 32 - 21

4x - 16 = 11

4x = 11 + 16

4x = 27

x = 27 : 4

x = 6,75.

7) 13x - 3x = 500

( 13 - 3 )x = 500

10x = 500

x = 500 : 10

x = 50.

8) 9x + x - 35 = 68

9x + 1x - 35 = 68

9x + 1x = 68 + 35

9x + 1x = 103

( 9 + 1 )x = 103

10x = 103

x = 103 : 10

x = 10,3.

1) 5x = 120 : 2

5x = 60

x = 60 : 5

x = 12.

2) 3x + 27 = 45

3x = 45 - 27

3x = 18

x = 18 : 3

x = 6.

3) 73 + x - 122 = 234 : 2

73 + x - 122 = 117

73 + x = 117 + 122

73 + x = 239

x = 239 - 73

x = 166.

4) 32 - 2 ( x - 1 ) = 12

2 ( x - 1 ) = 32 - 12

2 ( x - 1 ) = 20

x - 1 = 20 : 2

x - 1 = 10

x = 10 + 1

x = 11.

5) 3 ( x + 1 ) - 15 = 36

3 ( x + 1 ) = 36 + 15

3 ( x + 1 ) = 51

x + 1 = 51 : 3

x + 1 = 17

x = 17 - 1

x = 16.

6) 32 - ( 4x - 16 ) = 21

4x - 16 = 32 - 21

4x - 16 = 11

4x = 11 + 16

4x = 27

x = 27 : 4

x = 6,75.

7) 13x - 3x = 500

( 13 - 3 )x = 500

10x = 500

x = 500 : 10

x = 50.

8) 9x + x - 35 = 68

9x + 1x - 35 = 68

9x + 1x = 68 + 35

9x + 1x = 103

( 9 + 1 )x = 103

10x = 103

x = 103 : 10

x = 10,3.

mình chịu thôi!lêu...lêu...lêu

a) 5x = 120 : 2

5x = 60

x = 60 : 5

x = 12

b) 3x + 27 = 45

3x = 45 - 27

3x = 18

x = 18 : 3

x = 6

c) 73 + x - 122 = 234 : 2

73 + x - 122 = 117

73 + x = 117 + 122

73 + x = 239

x = 239 - 73

x = 166

d) 32 - 2(x - 1) = 12

2(x - 1) = 32 - 12

2(x - 1) = 20

x - 1 = 20 : 2

x - 1 = 10

x = 10 + 1

x = 11

e) 3(x + 1) - 15 = 36

3(x + 1) = 36 + 15

3(x + 1) = 51

x + 1 = 51 : 3

x + 1 = 17

x = 17 - 1

x = 16

f) 21 - (4x - 16) = 21

4x - 16 = 21 - 21

4x - 16 = 0

4x = 0 + 16

4x = 16

x = 16 : 4

x = 4

g) 13x - 3x = 500

10x = 500

x = 500 : 10

x = 50

h) 9x + x - 35 = 65

10x - 35 = 65

10x = 65 + 35

10x = 100

x = 100 : 10

x = 10

\(=\dfrac{1}{15}+\dfrac{2}{15}+\dfrac{3}{15}+...+\dfrac{9}{15}\)

\(=\dfrac{1+2+3+...+9}{15}\)

\(=\dfrac{45}{15}=3\)