Bonsoir,
A = -1/2 + 5/2 (1 - 1/2)
A = -1/2 + 5/2 (2/2 - 1/2)
A = -1/2 + 5/2 x 1/2
A = -1/2 + 5/4
A = -2/4 + 5/4
A = 3/4
B = 5/7 : 6/7 - (1/2 - 1)
B = 5/7 x 7/6 - (1/2 - 2/2)
B = 5/6 x 7/7 - (-1/2)
B = 5/6 + 1/2
B = 5/6 + 2/4
B = 10/12 + 6/12
B = 16/12
B = 4/3
A = 3/4 et B = 4/3 ils sont donc bien inverses l’un de l’autre