Bonsoir , besoin d'aide svp sur cette exercice de math, mercii ; Simplifier les fractions : A= 9/21-4/21 B=10/24+21/36 C=9/1-15/2-3/2 D=1/1-5/8+3/8 E=7/18+2/6+5

Bonsoir,

Pour additionner ou soustraire des fractions, il faut d'abord les mettre sur le même dénominateur.

A = 9/21 - 4/21

A = (9-4)/21

A = 5/21

B = 10/24 + 21/36

B = (2×5)/(2×12) + (3×7)/(3×12)

B = 5/12 + 7/12

B = (5 + 7)/12

B = 12/12

B = 1

C = 9/1 - 15/2 - 3/2

C = (2×9)/(2×1) - 15/2 - 3/2

C = 18/2 - 15/2 - 3/2

C = (18 - 15 - 3)/2

C = 0/2

C = 0

D = 1/1 - 5/8 + 3/8

D = 8/8 - 5/8 + 3/8

D = (8-5+3)/8

D = 6/8

D = 3/4

E = 7/18 + 2/6 + 5/9

E = 7/18 + (2×3)/(6×3) + (5×2)/(9×2)

E = 7/18 + 6/18 + 10/18

E = (7+6+10)/18

E = 23/18

F = (1/10 + 1/30) - (1/5 - 1/15)

F = (3/30 + 1/30) - (3/15 - 1/15)

F = 4/30 - 2/15

F = 4/30 - 4/30

F = 0

G = 11/7 + 7/49 + 6/21

G = (11×7)/(7×7) + 7/49 + 14/49

G = 77/49 + 7/49 + 14/49

G = (77+7+14)/49

G = 98/49

G = 2

H = 8/5 - (1/10 + 2/10)

H = 16/10 - 3/10

H = 13/10