Résoudre les équations suivantes : al 3x + 7 = 11; b/ 4x-12 = x; c 3x + 11 = 4x-12; d/ 6-11 = 9x + 15; el - 3x + 11 = 4x-17; f -2x-11 =-3x+13; g 5- 4x = -3x; b/

a. 3x +7 = 11

3x = 11 - 7

3x = 4

x = 3/4 = 1,3

b. 4x - 12 = x

4x - x = 12

3x = 12

x = 4

c. 3x + 11 = 4x - 12

3x - 4x = - 12 - 11

- x = - 23

x = 23

Réponse :

a) 3x+7=11

3x= 11-7

3x= 4

x= 4/3

b) 4x-12 = x

   4x+x=12

    5x= 12

    x= 12/5

c) 3x+11 = 4x-12

   3x -4x = -12-11

   -x= -23

    x= 23

d) 6-11 = 9x+15

   -9x= 15-6+11

    -9x = 20

     x= [tex]\frac{20}{-9}[/tex]

e) -3x+11 = 4x -17

   -3x-4x = -17-11

   -7x = -29

    x= -27/ -7

    x= 27/7

f) -2x-11 = -3x+13

  -2x+3x= 13+ 11

   x= 24

g) 5-4x = -3x

   -4x+3x = -5

    -x = -5

     x= 5

h) 4x +7 = 2x+7

   4x-2x= 7-7

    2x = 0

     x= 0

i) 3x -11 = 3x +17

3x-3x = 17-11

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