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Meilleure réponse !
2014-09-14T09:41:34+02:00
Exercice 2

C = 1/3 + 2/5
C = 1 x 5 / 3 x 5 + 2 x 3 / 5 x 3
C = 5/15 + 6/15
C = 11/15

D = - 7/11 + - 4/11
D = - 7/11 - 4/11
D = - 11/11
D = 11 x - 1 / 11 x 1
D = - 1/1
D = - 1

E = 14/25 x 5/21
E = 70/525
E = 35 x 2 / 35 x 15
E = 2/15

F = 7/8 + 10/3
F = 7 x 3 / 8 x 3 + 10 x 8 / 3 x 8
F = 21/24 + 80/24
F = 101/24

G = 5/3 - 4/3 x 5/2
G = 5/3 - 20/6
G = 5 x 2 / 3 x 2 - 20/6
G = 10/6 - 20/6
G = - 10/6
G = 2 x 5 / 2 x 3
G = 5/3

H = 2 + 2/3
     1/2 - 1/6
H = 2 x 3 / 1 x 3 + 2/3
     1 x 3 / 2 x 3 - 1/6
H = 6/3 + 2/3
       3/6 - 1/6
H = 8/3 : 2/6
H = 8/3 x 6/2
H = 48/6
H = 6 x 8 / 6 x 1
H = 8/1
H = 8

Exercice 4

1) Développer et réduire chaque expression :

A = 2 (x - 5)
A = 2x - 10

B = (x + 1) (2x - 3)
B = 2x² - 3x + 2x - 3
B = 2x² - x - 3

C = 3 (x² - 5) + (2x + 1)  (x + 4)
C = 3x² - 15 + 2x² + 8x + x + 4
C = 3x² + 2x² + 8x + x - 15 + 4
C = 5x² + 9x - 11

2) Calculer B pour x = - 2

B = (x + 1) (2x - 3)
B = (- 2 + 1) (2 (- 2) - 3)
B = (- 2 + 1) (- 4 - 3)
B = 8 + 6 - 4 - 3
B = 13 - 7
B = 6