Bonjour,
Calculer sous la forme de fraction irréductible :
A=(3/7-8/21)x(7/12-3/18)
A = [(3 x 3) / (7 x 3) - 8/21] x [(7 x 3) / (12 x 3) - (3 x 2) / (18 x 2)]
A = (9/21 - 8/21) x (21/36 - 6/36)
A = 1/21 x 15/36
A = 15/756
A = (3 x 5) / (3 x 252)
A = 5/252
B=3/5-7/5:4/9x15
B = 3/5 - 7/5 x 9/4 x 15
B = 3/5 - 63/20 x 15
B = 3/5 - 945/20
B = (3 x 4) / (5 x 4) - 945/20
B = 12/20 - 945/20
B = - 933/20
C=-2/5+5/2x8/25:7/10
C = - 2/5 + 40/50 x 10/7
C = - 2/5 + 400/350
C = - 2/5 + (50 x 8) / (50 x 7)
C = - 2/5 + 8/7
C = (- 2 x 7) / (5 x 7) + (8 x 5) / (7 x 5)
C = - 14/35 + 40/35
C = 26/35
