EX5
exprimer sous forme fractionnaire simplifiée si possible
a) (3/4) + (1/8) = (3 x 2/8) + (1/8) = (6/8) + (1/8) = 7/8
b) (1/9) - (1/6) = (2/18) - (3/18) = - 1/18
c) 1 - (3/4) = (4/4) - (3/4) = 1/4
d) (5/9) + (5/6) = (5 x 2)/18 + ( 3 x 5)/18 = (10/18) + (15/18) = 25/18
e) (5/3) + (5/6) = 2 x 5/6) + (5/6) = 10/6) + (5/6) = 15/6 = (3 x 5)/(2 x 3) = 5/2
EX6
Reprendre l'exercice 5 avec
a) (7/10) - (5/4) = (7 x 4)/40 - (5 x 10)/40 = (28/40) + (50/40) = 78/40 = 2 x 39/2 x 20 = 39/20
b) (7/6) - (15/8) = (7 x 4)/24 - (15 x 3)/24 = 28/24) + (45/24) = (28+45)/24 = 73/24
c) (6/35) - (7/10) = (6 x 2)/70 - ( 7 x 7)/70 = (12 - 49)/70 = - 37/70
d) (- 15/8) + (12/15) = (- 15/8) + (3 x 4)/(3 x5) = (- 15/8) + (4/5) = (- 15 x 5)/40 + (32/40) = (-75/40) + (32/40) = - 35/40 = - 5 x 7/5 x 8 = - 7/8
