bonjour
a = 2/3 -2/3 x9/5
a = 2/3 -18/15
a = 10/15-18/15
a = -8/15
b = (1/6-1/3) : (2/5x3/4)
b = (1/6-2/6) : (6/20)
b = -1/6 : 3/10
b = -1/6 x 10/3
b = -10/18
b = -5/9
2/
B-A = -5/9 -(-8/15) = -5/9 +8/15 =-25/45 +24/45 = -1/45
AB = -8/15 x -5/9 = +40/ 135 = 8/27
A/B = -8/15 : -5/9 = -8/15 x -9/5 = +72/75= 24/25
3/
la somme de a et l inverse de b
-8/15 + (-9/5) = -8/15 -9/5 = -8/15 -27/15 =-35/15 = -7/3
le produit de b par l oppose de a
- 5/9 x +8/15 = -40/135 = -8/27