Bonjour,
Exercice 1
1)
5 544 = 2³ x 3² x 7 x 11
68 796 = 2² x 3³ x 7² x 13
2)
5 544/68 796
= [(2 x 2 x 3 x 3 x 7) x 2] / [(2 x 2 x 3 x 3 x 7) x (3 x 7 x 13)]
= (252 x 2) / (252 x 273)
= 2/273.
Exercice 2
1)
9/4 - 5/6 = (9 x 3) / (4 x 3) - (5 x 2) / (6 x 2) = 27/12 - 10/12 = 17/12
2)
10/21 x 14/15 = 140/315 = (35 x 4) / (35 x 9) = 4/9
3)
13/4 - 5/3 x 21/10 + 5/2
= 13/4 - 105/30 + 5/2
= 13/4 - (15 x 7) / (15 x 2) + 5/2
= 13/4 - 7/2 + 5/2
= 13/4 - 2/2
= 13/4 - 4/4
= 9/4
