4. Решите уравнение и сделайте проверку: а) 25y²-1=0;

25y² - 1 = 0
25y² = 1
y² = \(\frac{1}{25}\)
y = ±\(\sqrt{\frac{1}{25}}\)
y = ±\(\frac{1}{5}\)

Проверка:
1) y = \(\frac{1}{5}\): 25 * \(\frac{1}{5}\)² - 1 = 25 * \(\frac{1}{25}\) - 1 = 1 - 1 = 0
2) y = -\(\frac{1}{5}\): 25 * \(- \frac{1}{5}\)² - 1 = 25 * \(\frac{1}{25}\) - 1 = 1 - 1 = 0
Ответ: y₁ = \(\frac{1}{5}\), y₂ = -\(\frac{1}{5}\)