a) -[2x² - 6√2·x + 3y² +4√3·y +14] = -[(√2·x - 3)² + (√3·y + 2)² +1] < 0 deoarece
(√2x - 3)² ≥ 0 (√3y + 2)² ≥ 0
b) x^4 - 2x³ + 3x² - 2x +1,001 = x²(x² - 2x +1) +(x² -2x+1) + x² +0,001 =
= (x-1)² ·(x² +1) +x² +0,001 > 0 deoarece (x-1) ≥ 0 ; (x² +1) > 0; x² ≥ 0