Bonjour,

Exercice 1:

-5,5/-9

=5,5/9

=5,5×4/9×4

=22/36

-17/6

=-17×6/6×6

=-102/36

1,5/2

=1,5×18/2×18

=27/36

7/-12

=-7/12

=-7×3/12×3

=-21/36

-5/3

=-5×12/3×12

=-60/36

Exercice 2:

6/-13

=-6/13

=-6×3/13×3

=-18/39

-1/2

=-1×18/2×18

=-18/36

9/7

=9×2/7×2

=18/14

-2/11

=-2×9/11×9

=-18/99

3/-5

=-3/5

=-3×6/5×6

=-18/30

Exercice 3:

-21/15

= -21÷-3/15÷-3 = 7/-5

= -21×2/15×2 = -42/30

= -21÷7/15÷7 = -3/2,14

6/12

= 6÷-6/12÷-6 = -1/-2 = 1/2

= -21×-3/12×-3 = 63/-36

= 6×2/12×2 = 12/24

= 6×5/12×5 = 30/60