Réponses

2014-02-05T14:42:41+01:00
Exercice 39 :

a) 1,5/5 = 1,5 x 10 / 5 x 10 = 15/50 = 5 x 3 / 5 x 10 = 5/3

b) -2,7/3,6 = -2,7 x 10 / 3,6 x 10 = -27/36 = 9 x 3 / 9 x 4 = 3/4

c) 4,1/-2,5 = 4,1 x 10 / -2,5 x 10 = 41/-25 = -41/25

d) -1/-0,25 = -1 x 100 / -0,25 x 100 = -100/-25 = 25 x -4 / 25 x -1 = -4/-1 = -4/1

e) -1,21/7,7 = -1,21 x 100 / 7,7 x 100 = -121/770 = 11 x -11 / 11 x 70 = -11/70

f) -3,5/1,14 = -3,5 x 100 / 1,14 x 100 = -350/114 = 2 x - 175 / 2 x 57 = -175/57

Exercice 40 :

16/23 et 139/200
16/23 = 16 x 200 / 23 x 200 = 3200/4600
139/200 = 139 x 23 / 200 x 23 = 3197/4600

3197/4600 < 3200/4600
Donc :
139/200 < 16/23

Exercice 41 :

156/377 et 204/493
156/377 = 156 x 493 / 377 x 493 = 76908/185861
204/493 = 204 x 377 / 493 x 377 = 76908/185861

Oui ces fractions  sont  égales car 76908/185621 = 76908/185861, donc :
156/377 = 204/496