1. (x-3) (2x-18) = 02. 2x^2-50=0 3. 3x^2-7x+4=0

Найдем корни.

1. (x - 3) * (2 * x - 18) = 0;

{ x - 3 = 0;

2 * x - 18 = 0;

{ x = 3;

2 * x = 18;

{ x = 3;

x = 18/2;

{ x = 3;

x = 9.

2. 2 * x^2 - 50 = 0;

2 * x^2 = 50;

x^2 = 50/2;

x^2 = 25;

x^2 - 25 = 0;

(x - 5) * (x + 5) = 0;

{ x - 5 = 0;

x + 5 = 0;

{ x = 5;

x = - 5.

3. 3 * x^2 - 7 * x + 4 = 0;

D = b^2 - 4 * a * c = (-7) ^2 - 4 * 3 * 4 = 49 - 16 * 3 = 49 - 48 = 1;

x1 = (7 + 1) / (2 * 3) = 8/6 = 4/3;

x2 = (7 - 1) / 6 = 6/6 = 1.