
Решим уравнение:
5y² - 9y - 2 = 0
D = b² - 4ac = (-9)² - 4 * 5 * (-2) = 81 + 40 = 121
y₁ = (-b + √D) / 2a = (9 + √121) / (2 * 5) = (9 + 11) / 10 = 20 / 10 = 2
y₂ = (-b - √D) / 2a = (9 - √121) / (2 * 5) = (9 - 11) / 10 = -2 / 10 = -0.2
Ответ: y = 2; y = -0.2