Réponse :
Bonsoir
Explications étape par étape
Exercice 1 :
1) +9 +(-12) = 9 -12 = -3
2) 12- (+9) = 12-9 = 3
3) +7 -(-1) = 7+1 = 8
4) -10.3 - (-6.3) = -10.3 + 6.3 = -4
Exercice 2:
1) 9x - 2x = 7x
2) 2x -9x = -7x
3) 5x - 9x +10x = 15x - 9x = 6x
4) -4x +10.5x= 6.5x
Exercice 3:
1) 5x -10 = 7.5
5x = 17.5
x = 17.5 / 5
x = 3.5
2) 2x + 4 = 6x - 48
4+ 48 = 6x -2x
4x = 52
x = 52/4
x = 6.25
3) 8x -2 = 54
8x = 54 +2
8x = 56
x = 56/8
x = 7
4) 13x -21 = 7x +15
13x -7x = 21+15
6x = 36
x= 6
