Sagot :
Bonjour
A = 1/3 + 2 (5/7 - 1)
A = 1/3 + 10/7 - 2
A = (1 x 7) / (3 x 7) + (10 x 3) / (7 x 3) - (2 x 21) / (1 x 21)
A = 7/21 + 30/21 - 42/21
A = - 5/21
B = (1 - 1/3) : (1 + 1/3)
B = [(1 x 3) / (1 x 3) - 1/3)] : [(1 x 3) / (1 x 3) + 1/3]
B = (3/3 - 1/3) : (3/3 + 1/3)
B = 2/3 : 4/3
B = 2/3 x 3/4
B = 6/12
B = (6 x 1) / (6 x 2)
B = 1/2
C = - 2 (1/3 : 5 + 1)
C = - 2 (1/3 x 1/5 + 1)
C = - 2 (1/15 + 1)
C = - 2/15 - 2
C = - 2/15 - (2 x 15) / (1 x 15)
C = - 2/15 - 30/15
C = - 32/15
D = (5 + 7/2) : 5
D = [(5 x 2) / (1 x 2) + 7/2] : 5
D = (10/2 + 7/2) : 5
D = 17/2 : 5
D = 17/2 x 1/5
D = 17/10.