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Meilleure réponse !
2014-10-08T16:37:09+02:00
Exercice 1
A = 9/4 x 1/5 = 9/(4x5) = 9/20
B = 10/7 : 1/9 = 10/7 x 9/1 = 90/7 
C = -3/2 x -5/-8 = (-3x-5)/(2x-8) = 15/-16 = -15/16
D = -9/4 : -2/5 = -9/4 x 5/-2 = (-9x5) / (4x-2) = -45/-8 = 45/8
E = 5/8 : 35/16 = 5/8 x 16/35 = (5x16) / (8x35) = (5x2x8) / (8x5x7) = 2/7
F = 27/4 x 8/81 = (27x8) / (4x81) = (9x3x2x4)/(4x9x9) = (3x2)/9 =(3x2)/(3x3) = 2/3

G = -30/50 : -27/-30 = -3/5 x -30/-27 = (-3x-30)/(5x-27) = (3x6x5)/(5x3x-9)
G = 6/-9 = -(3x2)/(3x3) = -2/3

H = 20/-35 x 35/-4 = (4x5x35)/(-35x-4) = 5/1 = 5

Exercice 2
A = 11/4 +3/4 x -7/12 = 14/4 x -7/12 = 7/2 x -7/12 = -49/24
B = -6/19 +6/19 : 3/26 = 0/19 : 3/26 = 0

C = 14/11 + (-3)/11 - (-13/7) = (14-3)/11 + 13/7 = 11/11 +13/7
C = 1+13/7 = 7/7 + 13/7 = 20/7

D = -9/28 + (-5)/28 -1/3 = -14/28 -1/3 = -7/14 - 1/3
D = (-7x3)/(14x3)-(14x1)/(3x14) = -21/42 -14/42 = -35/42

E = -3/2 : (-14/13 +9/13) = -3/2 : -5/13 = -3/2 x 13/9 = (-3x13)/(2x3x3) = -13/6

F = -12/35 : (-7/30+(-11)/30) = -12/35 : -18/30 = -12/35 x 30/-18
F = (-12x30)(35x-18) = (-2x6 x 6x5)/(9x5x-9x2) = (-6x6)/(9x-9)
F = (-2x3x2x3)/(3x3x-9) = (-2x2)/-9 = -4/-9 = 4/9