Bonjour
Calculer les expressions suivantes(avec toutes les étapes de calcul):
a)1/3+2/3÷5/7
= 1/3 + 2/3 x 7/5
= 1/3 + 14/15
= (1 x 5) / (3 x 5) + 14/15
= 5/15 + 14/15
= 19/15
b)5/4-3/2÷-2/5+1/4
= 5/4 - 3/2 x 5/2 + 1/4
= 6/4 - 15/4
= - 9/4
c)-7/3×2/7÷-3/7×14/3
= - 14/21 x - 7/3 x 14/3
= 98/63 x 14/3
= 1 372/189
= (7 x 196) / (7 x 27)
= 196/27
d)-2÷5/12-3/4
= - 2 x 12/5 - 3/4
= - 24/5 - 3/4
= (- 24 x 4) / (5 x 4) - (3 x 5) / (4 x 5)
= - 96/20 - 15/20
= - 111/20.
e)2-4/3÷-2
= 2 - 4/3 x - 1/2
= 2 + 4/6
= (2 x 3) / (1 x 3) + (2 x 2) / (2 x 3)
= 6/3 + 2/3
= 8/3
f)9/2×(7/9-5/12)
= 9/2 x [(7 x 4) / (9 x 4) - (5 x 3) / (12 x 3)]
= 9/2 x (28/36 - 15/36)
= 9 /2 x 13/36
= 117/72
= (9 x 13) / (9 x 8)
= 13/8.