Réponses

2014-04-07T16:48:59+02:00
Exercice 4
l'inverse de 10/7 est 7/10 donc C, D, H car 7/10 = (7x7)/(10x7) = 49/70 et H car (7/10 = (2x7)/(2x10 = 14/20

Exercice 7
E = (5/7):(13/11) = 5/7 x 11/13 = 55/91

F = (4/9):(-1/4) = 4/9 * -4/1 = 16/9

G = (5/3):(7/2) = 5/3 x 2/7 = 10/21

H = (1/4):(1/3) = 1/4 x /73/1 = 3/4

J = (9/10) : (5/11) = 9/10 x 11/5 = 99/50

K = (-18/7):(5/4) = -18/7 x 4/5 = 72/35

Exercice 11

a^-1 se lit a puissance -1
a = 5 ; a^-1 = 1/5
a^-1 = 4 ; a = 1/4
a = -2/3 ; a^1 = -3/2
a^-1 = 4/5 ; a = 5/4
a = 1,5 = 3/2 ; a^-1 = 2/3

b. l'inverse de l'inverse d'un nombre est ce nombre (exemple : l'inverse de l'inverse de 4 est 4)

Exercice 12
^ se lit puissance : par exemple 2^-3 se lit 2 puissance -3
a. 2^-3 = 1/2^3 = 1/8

b. (-5)^-3 = -1/5^3 = -1/125

c. 3^-2 = 1/3^2 = 1/9

d. 7^-1 = 1/7

e. 10^-3 = 1/10^3 = 1/1000

f. (2.5)^-4 = (5/2)^-4 = 5^-4/2^-4 = (1/5^4)/(1/2^4) = 1/5^4 x 2^4/1 = 2^4/5^4 = 16/625