Sagot :
bjr
0! = 1
1! = 1
2! = 1 x 2 = 2
3! = 1 x 2 x 3 = 6
A = 1 + 1 + 1/2 + 1/6 = 2 + 1/2 + 1/6 (dénominateur commun 6)
= 12/6 + 3/6 + 1/6
= (12 + 3 + 1)/6
= 16/6
A = 8/3
8/3 = 2,66666....
A = 2,6666 valeur approchée au dix-millième
--------------
4! = 1 x 2 x 3 x 4 = 24
5! = 24 x 5 = 120
B = A + 1/4! + 1/5! = 8/3 + 1/24 + 1/120 (on associe les deux derniers)
= 8/3 + 5/120 + 1/120
= 8/3 + 6/120 (on simplifie 6/120)
= 8/3 + 1/20 (dénominateur commun 60)
= (8 x 20)/60 + 3/60
= 160/60 + 3/60
B = 163/60
163/60 = 2,7166666....
B = 2,7166 valeur approchée
-----------------------
6! = 120 x 6 = 720
7! = 720 x 7 = 5040
C = 163/60 + 1/720 + 1/5040 (dénominateur commun 5040)
C = 163 x 84 /60 x 84 + 7/(720 x 7) + 1/5040
C = (13692 + 7 + 1)/5040
C = 13700/5040
13700 / 5040 = 1370/504 = 685/252
C = 685/252
685/252 = 2.7182539...
C = 2,7182 valeur approchée