bonjour aider moi svp​

Réponse :

Explications étape par étape

Bjr,

Exercice 9

5a-3a =5 -4

2a = 1

a = 1/2

2a-5+7a = 3a+3

2a+7a-3a =3 +5

6a = 8

a = 8/6 = 4/3

Exercice 10

15x/15 -5/15 = 6x/15 +1/15

15x/15 -6x/15 = 1/15 +5/15

9x/15 = 6/15

3x/5 = 2/5

3x = (2*5)/5 = 10/5 = 2

x = 2/3

exercice 11

-5-3 = 4x-2x

-8 = -2x

-8/-2 = x

x= 4

x/2 -4x/3 = -7-3,5

3x/6  -8x/6 = -10,5

-5x/6 = -10,5

-5x = -10,5 *6 = -63

x = 63/5

3x+12 -7 = 15 -2x

3x+2x = 15 -12 +7

5x = 10

x= 10/5 = 2