bonjour,
-6 ≤ x ≤ -3 et -2 ≤ y ≤ -1
* -6+(-2) ≤ x+y ≤ -3+(-1)
-8 ≤ x+y ≤ -4
*1 ≤- y ≤ 2
-6+1 ≤ x+(-y) ≤-3+2
-5 ≤ x-y ≤ -1
* -3.-1≤ xy ≤ -6.-2
3≤ xy ≤ 12
* -6 ≤ x ≤ -3
(-3)²≤x²≤(-6)²
9≤x²≤36
*-2 ≤ y ≤ -1
5 ≤- 5y ≤ 10
*-2 ≤ y ≤ -1
-1 ≤1\y ≤ -1\2
-1\2 . -3 ≤x.1\y ≤ -6 . -1
3\2 ≤x\y ≤ 6
