Bonsoir
Je nomme "a" les nombres manquants qu'on cherche
Exercice 26
A. 7 x a = 3
a = 3 / 7
7 x 3/7
= (7 x 3) / 7
= 21 / 7
= 3
B. a x 5 = 8
a = 8 / 5
8/5 x 5
= (8 x 5) / 5
= 40 / 5
= 8
C. a = 13 : 11
a = 13/11
D. 13 x a = 11
a = 11 / 13
13 x 11/13
= (13 x 11) / 13
= 143 / 13
= 11
Exercice 27
A. a x 6 = 9
a = 9 / 6
a = (9 / 3) / (6 / 3)
a = 3 / 2
a = 1.5
B. a x 12 = 7.2
a = 7.2 / 12
a = (7.2 x 10) / (12 x 10)
a = 72 / 120
a = (72 / 6) / (120 / 6)
a = 12 / 20
a = (12 / 4) / (20 / 4)
a = 3 / 5
a = 0.6
C. a x 14 = 35
a = 35 / 14
a = (35 / 7) / (14 / 7)
a = 5 / 2
a = 2.5
D. a x 25 = 1
a = 1 / 25
a = 0.04
Voilà j'espère avoir pu t'aider ^^
