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.