Salut!
Răspuns:
A = { x € Z | | x | = 4 si | x | = 9 }
| x | = 4 ===> x € { -4; 4 }
| x | = 9 ===> x € { -9; 9 }
A = { -9; -4; 4; 9 }
B = { x € Z | x + 1 >= -1 si | x + 2 | < 4 }
[tex]x + 1 \geqslant - 1 \\ x \geqslant - 1 - 1 \\ x \geqslant - 2
x € { -2; -1; 0; 1; 2... }
| x + 2 | < 4 ===> 1 ) x + 2 < 4
2 )x + 2 < -4
1 ) x + 2 < 4
x < 4 - 2
x < 2
x € { 1; 0 ; -1 ... }
2 ) x + 2 < -4
x < -4 - 2
x < -6
x € { -7 ; -8 -9 ... }
B = { -7; -8; -9 ... }
