3. Найти корни уравнения: a, b, c

3. a. \( 2x^2 - 50 = 0 \): \( x^2 = 25, x = \pm 5 \). b. \( 15x - x^2 = 0 \): \( x(15 - x) = 0, x_1 = 0, x_2 = 15 \). c. \( \frac{x^2}{5} - 1 = 0 \): \( x^2 = 5, x = \pm \sqrt{5} \).