Réponses

2014-01-28T17:26:02+01:00
1 + 1/7 + 1/21 + 1/84 + 1/140
= 1 x 60 / 7 x 60 + 1 x 20 / 21 x 20 + 1 x 3 / 140 x 3
= 60/420 + 21/420 + 3/420
= 81/420 + 3/420
= 84/420
= 84 x 1 / 84 x 5
= 1/5