3. Решите уравнение: a) x² - 15² = 0 б) 49 - 36y² = 0 в) (9 - y)² - y(y + 1) = 65

a) x² - 15² = 0 x² = 225 x = ±√225 x = ±15 б) 49 - 36y² = 0 36y² = 49 y² = 49/36 y = ±√(49/36) y = ±7/6 в) (9 - y)² - y(y + 1) = 65 81 - 18y + y² - y² - y = 65 81 - 19y = 65 -19y = 65 - 81 -19y = -16 y = 16/19