Bonsoir á tous, je suis en 4ème , je n'arrive absoluement pas á faire exercice de maths. Pourriez-vous m'aidé car je ne comprend pas. Exercice: Calculer les exp

a) 8/5 + 7/5 x 3/5 = 8/5 + 21/25 = (8 x 5)/(5 x 5) + 21/25 = 40/25 + 21/25 = 61/25

b)53/30 - ( 6/10 + 8/10) = 53/30 - 6/10 - 8/10 = 53/30 - 14/10 = 53/30 - (14 x 3)/(10 x 3) = 53/30 - 42/30 = 11/30

c) 7/6 x 7/2 - 3/2 = 49/12 - 3/2 = 49/12 - (3 x 6)/(2 x 6) = 49/12 - 18/12 = 31/12

d) 3/7 + (17/14 - 23/28) = ((17 x 2)/(14 x 2) - 23/28) = 3/7 + (34/28 - 23/28) = 3/7 - 11/28 = (3 x 4)(7 x 4) - 11/28 = 12/28 - 11/28 = 1/28

e) (8/5 + 7/5) x 3/5 = (8 x 3)/(5 x 5) + (3 x 7)/(5 x 5) = 24/25 + 21/25 = 45/25

f) 53/30 - 6/10 + 8/10 = 53/30 - 2/10 = 53/30 - (2 x 3)/(10 x 3) = 53/30 - 6/30 = 47/30

g) 7/6 x (7/2 - 3/2) = (7 x 7)/(6 x 2) - (7 x 3)/(6 x 2) = 49/12 - 21/12 = 28/12

h) 3/7 + 17/14 - 23/28 = 3/7 + (17 x 2)/(14 x 2) - 23/28 = 3/7 + 14/28 - 23/28 = 3/7 - 14/28 = (3 x 4)/(7 x 4) - 14/28 = 12/28 - 14/28 = -(2/28)

Voilà :)

a)
8:5 + 7:5 x 3:5
8/5 + 21/25
40/25 + 21/25 = 61/25


b)
53:30 - ( 6:10 + 8:10)
53/30 - 14/10
53/30 - 42/30 = 11/30


c)
7:6 x 7:2 - 3:2
49/12 - 3/2
49/12 - 18/12 = 31/12


d)
3:7 + (17:14 - 23:28)
3/7 + ( 34/28 - 23/28 )
3/7 + 11/28
12/28 + 11/28 = 23/28

e)
(8:5 + 7:5) x 3:5
15/5 x 3/5
3 x 3/5 = 9/5


f)
53:30 - 6:10 + 8:10
53/30 - 6/10 + 8/10
53/30 - 18/30 + 24/30
35/30 + 24/30 = 59/30 


g)
7:6 x (7:2 - 3:2)
7/6 x 4/2
7/6 x 2 = 14/6 = 7/3


h)
3:7 + 17:14 - 23:28
3/7 + 17/14 - 23/28
12/28 + 34/28 - 23/28
46/28 - 23/28 = 23/28