Réponse :
Bonjour
Explications étape par étape
Equations
Exercice 9
5a +4 = 3a +5
5a -3a = -4 +5
2a = 1
a = 1/2
2a -5 +7a = 3(a +1)
2a -5 +7a = 3a +3
2a -3a +7a = +5 +3
6a = 8
a = 8/6
a = 4/3
Exercice 10
x -1 = 2x +1 =
3 5 15
15x -5 = 6x +1
15 15
15x -5 = 6x +1
15x -6x = +5 +1
9x = 6
x = 6/9
x = 2/3