4. Решите уравнение и сделайте проверку: б) -y²+2=0;

-y² + 2 = 0
-y² = -2
y² = 2
y = ±\(\sqrt{2}\)

Проверка:
1) y = \(\sqrt{2}\): -\(\sqrt{2}\)² + 2 = -2 + 2 = 0
2) y = -\(\sqrt{2}\): -\(-\sqrt{2}\)² + 2 = -2 + 2 = 0
Ответ: y₁ = \(\sqrt{2}\), y₂ = -\(\sqrt{2}\)