Réponse :Bonjour,
Exercice 48.
a. -5/14 - 3/7 = -5/14 - 3*2 / 7*2 = -5-6 / 14 = -11/14
b. 2/9 - 5/27 = 2*3 / 9*3 = 6 / 27 - 5/27 = 1/27
c. -3/20 - 2/5 = - 3/20 - 2*4 / 5*4 = -3 - 8 / 20 = -11 / 20
Exercice 49.
a. 3/4 - 11/12 = 3*3 / 4*3 - 11/12 = 9 / 12 - 11/12 = -2 / 12 = - 1 / 6
b. 3/4 + 11/12 = 3*3 / 4*3 + 11/12 = 9 + 11 / 12 = 20 /12 = 5*4 / 3*4 = 5/3
c. 5*3 / 6* 3 - 7 / 18 =15 -7 / 18 = 8 / 18 =
Exercice 54.
a. 2/7 + 4/9 = 18/63 + 28/63 = 46 / 63
b. 3/8 - 5/3 = 9/24 - 40 / 24 = -31/ 24
c. -4/5 - 7/9 = -36/45 - 35/45 = -71 / 45
d. 1+2/9 = 9/9 + 2/9 = 11/9
e. 3/3 - 7/3 = -4/3
f. 3*4/ 1*4 + 3/4 = 12 + 3 / 4 = 15/4
