bonjour a toutlemonde jai un prebleme sur les equations svp aidez moi exe.7Resoudre les equations dinconnue x suivantes a.-2x+7=-x+9 b.4x-21=7x-9 c.-7x-12=8x+3

Bonjour,

-2x + 7 = -x + 9

- 2x + x = 9 - 7

- x = 2

x = - 2

4x - 21 = 7x - 9

4x - 7x = - 9 + 21

- 3x = 12

x = -12/3 = -4

- 7x - 12 = 8x + 3

- 7x - 8x = 3 + 12

- 15x = 15

x = -15/15 = -1

7x + 3 = - 3x - 7

7x + 3x = - 7 - 3

10x = -10

x = -10/10 = -1

Réponse :

Bonjour voici ce que j'ai trouvé A) x = -2 B) x = -4  C) = -1  D) = -2

Explications étape par étape

A ) -2x + 7 = -x + 9

- 2x + x = +9-7

-1x = +2

x = 2/-1    x = -2

B)  4x - 21 = 7x - 9

4x - 7x = -9 + 21

-3x = +12

x = 12/-3   x = -4

C) -7x - 12 = 8x + 3

-7x - 8x = +3 + 12

- 15x = +15

x = 15/ -15   x = -1

D) 7x + 13 = -3x -7

7x +3x = -7 - 13

10x = -20

x = -20/10   x=-2