Bonjkur , je suis en 5eme etj ais un DM a rendre mqis jy comprend riienn :( Svp HELP ! <3

Calculer chaque expression sachant que ;

M= 1 neuvieme ; N= 2 tiers ; P=5 sur 18

a) m+n b) p -m c) np.
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Exercice 2 ;

A =3 huitieme fois (4 neuvieme + 2 tiers)

B= 3huitieme fois 4 neuvieme + 2 tiers

C = 7 cinquieme fois ( 3 dixieme + 1 cinquieme)

D = 7 cinquieme fois 3 dixieme + 1 sur 5 .

Merci de votre aide ! ;)

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Meilleure réponse !
2014-04-09T23:32:38+02:00
Calculer chaque expression sachant que :

M = 1/9 ; N = 2/3 ; P = 5/18

a) m + n
1/9 + 5/18
= 1 x 2 / 9 x 2 + 5/18
= 2/18 + 5/18
= 7/18

b) p - m
5/18 - 1/9
= 5/18 - 1 x 2 / 9 x 2
= 5/18 - 2/18
= 3/18
= 3 x 1 / 3 x 6
= 1/6

c) np
2/3 x 5/18
= 2 x 5
  3 x 18
= 10/54
= 2 x 5 / 2 x 27
= 5/27
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Exercice 2 ;

A = 3/8 x (4/9 + 2/3)
A = 3/8 x (4/9 + 2 x 3 / 3 x 3)
A = 3/8 x (4/9 + 6/9)
A = 3/8 x 10/9
A = 3 x 10
       8 x 9
A = 30/72
A = 6 x 5 / 6 x 12
A = 5/12

B = 3/8 x 4/9 + 2/3
B = 3 x 4 + 2/3
      8 x 9
B = 12/72 + 2/3
B = 12/72 + 2 x 24 / 3 x 24
B = 12/72 + 48/72
B = 60/72
B = 12 x 5 / 12 x 6
B = 5/6

C = 7/5 x (3/10 + 1/5)
C = 7/5 x (3/10 + 1 x 2 / 5 x 2)
C = 7/5 x (3/10 + 2/10)
C = 7/5 x 5/10
C = 7 x 5
      5 x 10
C = 35/50
C = 5 x 7 / 5 x 10
C = 7/10

D = 7/5 x 3/10 + 1/5

D = 7 x 3 + 1/5
      5 x 10
D = 21/50 + 1 x 10 / 5 x 10
D = 21/50 + 10/50
D = 31/50