Bonjour
Exercice I
1) 3/8 = 21/56 = 7/8
36/45 = 4/5
2) 3/4 et -2/5 = 15/20 et - 8/20
- 5/6 et -11/9 = - 15/18 et - 22/18
3) -9/6 et -12/8 = - 1.5 et -1.5 donc oui
10/35 et 8/21 = 0.28 et 0.38 donc non
Exercice II
A = 5/8 + 7/12 = 15/24 + 14/24 = 29/24
B = 3/20 - 5/12 = 36/240 - 60/240 = - 24/240 = - 1/10
C = 5/42 - (-7/12) = 5/42 +7/12 = 10/84 + 49/84 = 59/84
D = 3/5 - 5/25 +1/15 = 45/75 - 15/75 + 5//75 = 35/75 = 7/15
