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Hello !

27) C'est toujours le même principe :

a) 3/5 × 7/2 = (3×7)/(5×2) = 21/10

b) 1/4 × 3/5 = (1×3)/(4×5) = 3/20

c) 9/5 × 7/9 = (9×7)/(5×9) = 63/45 = 7/5

28)

b) 4/7 × 5/2 = (4×5)/(7×2) = 20/14 = 10/7

c) 7/3 × 6/5 = (7×6)/(3×5) = 42/15 = 14/5

A toi de jouer pour les autres ;-)

Bonne nuit !

Réponse :

Explications étape par étape

Bonjour

Exercice 27 :

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

1/4 x 3/5 = (1 x 3)/(4 x 5) = 3/20

9/5 x 7/9 = 9/9 x 7/5 = 1 x 7/5 = 7/5

Exercice 28 :

5/11 x 2/5 = 5/5 x 2/11 = 2/11

4/7 x 5/2 = 4/2 x 5/7 = 2 x 5/7 = 10/7

7/3 x 6/5 = 6/3 x 7/5 = 2 x 7/5 = 14/5

Exercice 29 :

-2/7 x 14/16 = -2/16 x 14/7 = -1/8 x 2 = -2/8

-3/5 x -15/7 = 15/5 x 3/7 = 3 x 3/7 = 9/7

-4/3 x 3/5 = 3/3 x -4/5 = -4/5

Exercice 30 :

-1/5 x 5/-3 = 5/5 x 1/3 = 1/3

-3/5 x 7/9 = -3/9 x 7/5 = -1/3 x 7/5 = -7/15

-5/-4 x 2/15 = 2/4 x 5/15 = 1/2 x 1/3 = 1/6