1) $$3x - x^2 = 0$$
$$x(3-x) = 0$$
$$x_1 = 0$$
$$3 - x = 0$$
$$x_2 = 3$$
Ответ: 0; 3
2) $$y^2 + 5y = 0$$
$$y(y+5) = 0$$
$$y_1 = 0$$
$$y + 5 = 0$$
$$y_2 = -5$$
Ответ: 0; -5
3) $$11x^2 - x = 0$$
$$x(11x - 1) = 0$$
$$x_1 = 0$$
$$11x - 1 = 0$$
$$11x = 1$$
$$x_2 = \frac{1}{11}$$
Ответ: 0; $$\frac{1}{11}$$
4) $$9x^2 + 6x = 0$$
$$3x(3x + 2) = 0$$
$$3x = 0$$
$$x_1 = 0$$
$$3x + 2 = 0$$
$$3x = -2$$
$$x_2 = -\frac{2}{3}$$
Ответ: 0; -$$\frac{2}{3}$$