1. √(x² + 2x +1) +9 + √(y² -6y +9) + 16 ≤ 7
√( x +1)² + 9 + √( y -3)²+16 ≤ 7
↓ ↓
=0 = 0
daca x +1 =0 si y -3 = 0
x = -1 y = 3
atunci √9 + √16 = 3 + 4 ≤ 7
2. √a² = I a I
I 2x - 3 I ≤ 1
cu definitia - 1 ≤ 2x - 3 ≤ 1 adunam 3
- 1 + 3 ≤ 2x -3 + 3 ≤ 1 +3
2 ≤ 2x ≤ 4 impartim cu 2
1 ≤ x ≤ 2 ; x∈ Z
x∈ { 1 ; 2}
3. √2ab∈N daca ab = 18 ; 32 ; 50 ; 72 ; 98
√2ab = patrat perfect
√2·18 = √36 = 6 ; √2·32= √64=8 ; √2·50 = √100 =10
√2·72=√144 = 12 ; √2·98 = √196 = 14
18 + 32 + 50 + 72 + 98 = 270
