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2014-02-15T12:08:19+01:00
Exercice 61

a) x + y + z = -5 + 4 + (-2,5) = -1 -2,5 = -3,5

b) x y z = -5 x 4 x -2,5 = -20 x -2,5 = 50

c) x - y z = -5 - ( 4 x - 2,5) = -5 - (-10) = -5 + 10 = 5

Exercice 23

A = 3/7 + 5/2
A = 3 x 2 / 7 x 2 + 5 x 7 / 2 x 7
A = 6/14 + 35/14
A = 41/14

B = -5/3 + 7/8
B = -5 x 8 / 3 x 8 + 7 x 3 / 8 x 3
B = -40/24 + 21/24
B = -19/24

c = -8/5 - 5/3
C = -8 x 3 / 5 x 3 - 5 x 5 / 3 x 5
C = -24/15 - 25/15
C = -49/15

D = 1/9 - -7/4
D = 1 x 4 / 9 x 4 - - 7 x 9 / 4 x 9
D = 4/36 - - 63/36
D = 4/36 + 63/36
D = 67/36