bonsoir , résoudre chaque équation : a. x+11=-7 b. 4x=9 c.-5x+9=3x-12

Réponse:

a. x + 11 = -7

x + 11 - 11 = - 7 - 11

x = - 18

b. 4x = 9

4x ÷4 =9÷ 4

x = 2,25

c. - 5x + 9 = 3x -12

5x + 9 - 9 =3x -12 - 9

5x - 3x = 3x - 21 - 3x

2x= -21

2x ÷ 2 = -21 ÷ 2

x = -10,5

bonjour

x+ 11 =  - 7

x = - 7 - 11

x = - 18

4 x = 9

x =  9/4

5 x + 9 = 3 x - 12

5 x -  3 x = - 12 - 9

2 x = - 21

x = - 21/2