bonjour,
exercice 1:
= 19/4 - [1/2-(3/8-1/4)
= 19/4 - [1/2-(3/8-2/8)
= 19/4 - [1/2-1/8]
= 19/4 - [4/8-1/8]
= 19/4 - 3/8
= 38/8 - 3/8
= 35/8
exercice 2:
a= 3
b= 5
c= -7
A= 1/a + 2/b - 3/c
A= 1/3 + 2/5 - 3/-7
A= 5/15 + 6/15 - 3/-7
A= 11/15 - 3/-7
A= 77/105 - 45/-105
A= 77/105 + 45/105
A= 122/105
B= b/a + a/b
B= 5/3 + 3/5
B= 25/15 + 9/15
B= 34/15
bonne journée :)
