9 - 16y² = 0
16y² = 9
y² = \frac{9}{16}
y = ±\sqrt{\frac{9}{16}}
y = ±\frac{3}{4}
Проверка:
1) y = \frac{3}{4}: 9 - 16 * (\frac{3}{4})² = 9 - 16 * \frac{9}{16} = 9 - 9 = 0
2) y = -\frac{3}{4}: 9 - 16 * (- \frac{3}{4})² = 9 - 16 * \frac{9}{16} = 9 - 9 = 0
Ответ: y₁ = \frac{3}{4}, y₂ = -\frac{3}{4}