Bonjour, quelqu'un peut m'aider pour cet exercice svp c'est pour le lundi 13 mai. Merci d'avence :)

Réponse :

Bonjour,

2/

a) a/b = (-2/21)/(5/-7) = (-2/21)*(-7/5) = (-2*(-7))/(21*5) = 14/105 = (7*2)/(7*15) = 2/15

   a*b = (-2/21)*(5/-7) = (-2*5)/(21*(-7) = -10/(-147) = 10/147

   a+b = -2/21 + 5/(-7) = -2/21 - (3*5)/(3*7) = -2/21 - 15/21 = -17/21

   a-b = -2/21 - (5/(-7)) = -2/21 + 5/7 = -2/21 + 15/21 = 13/21

b) a/b = (5/24)/(35/18) = (5/24)*(18/35) = (5*18)/(24*35) = 90/840 = 9/84 = 3/28

   a*b = (5/24)*(35/18) = (5*35)/(24*18) = 175/432  

   a+b = 5/24 + 35/18 = (3*5/3*24) + (4*35/4*18) = 15/72 + 140/72 = 155/72

   a-b = 15/72 - 140/72 = -125/72