Bonsoir,
a.
4/10 = (2 x 2) / (2 x 5) = 2/5
8/14 = (2 x 4) / (2 x 7) = 4/7
2/20 = (2 x 1) / (2 x 10) = 1/10
66/50 = (2 x 33) / (2 x 25) = 33/25
100/198 = (2 x 200) / (2 x 99) = 200/99
b.
3/9 = (3 x 1) / (3 x 3) = 1/3
15/12 = (3 x 5) / (3 x 4) = 5/4
6/33 = (3 x 2) / (3 x 11) = 2/11
18/24 = (3 x 6) / (3 x 8) = 6/8 --> On peut aussi réduire par 2 : 6/8 = (2 x 3) / (2 x 4) = 3/4
21/15 = (3 x 7) / (3 x 5) = 7/5.
c.
7/21 = (7 x 1) / (7 x 3) = 1/3
28/70 = (7 x 4) / (7 x 10) = 4/10 --> On peut aussi réduire par 2 : 4/10 = (2 x 2) / (2 x 5) = 2/5.
35/49 = (7 x 5) / (7 x 7) = 5/7
63/42 = (7 x 9) / (7 x 6) = 9/6 --> On peut aussi réduire par 3 : 9/6 = (3 x 3) / (3 x 2) = 3/2
84/77 = (7 x 12) / (7 x 11) = 12/11.
