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Bonjour,

A= 1/5 - 8/15 x 5/4 = ?
B= -4/7 : (5/14 + 5/6) = ?

Mercii


Répondre :

bonjour

a = 1/5 - 10/60
a = 12/60 - 10/60 = 2/60 = 1/30

b = - 4/7 : ( 15/42 + 35/42)
b = - 4/7  : 50/42
b = - 4/7 x 42/50
b = - 168/350 = -12/25
A=1/5-8/15x5/4=1/5-(8/15x5/4)
8/15x5/4= 2x4x5/5x3x4=2/3
A= 1/5-2/3
1/5=3x1/5x3=3/15  2/3=2x5/3x5=10/15
A=3/15-10/15=-7/15

B=-4/7:(5/14+5/6)
5/14+5/6=
5/14=5x3/14x3=15/42
5/6=5x7/6x7=35/42
15/42+35/42=50/42=2x25/2x21=25/21
B=-4/7:25/21=-4/7x21/25=-4x3x7/7x25=-12/25