Réponse :
EXERCICE 13
A = 5/16 + 3/4 + 7/12 = 5x3 / 16x3 + 3x12/4x12 +7x4/12x4 = 15/48 + 36/48 + 28/48 = 79/48
B = -9/ 7 - ( 3 + 2/21 ) = -9/7 -3-2/21 = -9x3/7x3 -3/1 -2/21 = 27/21- 63/21 -2/21 = -38/21
C= 5/8 - 5/6 +1/3 = 5x3/8x3 - 5x4/6x4 +1x8 /3x8 = 15/24 - 20/24 + 8/24 = 3/24
