bonsoir

4/7 x 7/4 = 28/28 = 1

- 9  x  - 1/9 = 9/9 = 1

- 3/4 x - 4/3 = 12/12 = 1

- 1/1 x - 1/1 =  1 /1 = 1

Bonsoir,

4/7 x 7/4 = 1

-9 x 1/-9 = 1

-3/4 x 4/-3 = 1

-1/-1 x 1 = 1

Bonne soirée !