1) 5(2x-3)-(8x-7)=11-2x 2) 12x в квадрате + 17x-14=0

Найдем корешки.

1) 5 * (2 * x - 3) - (8 * x - 7) = 11 2 * x;

Скобки раскроем.

5 * 2 * x 5 * 3 8 * x + 7 = 11 2 * x;

10 * x 15 8 * x + 7 = 11 2 * x;

Приведем сходственные одночлены.

(10 * x 8 * x) + (7 15) = 11 2 * x;

2 * x 8 = 11 2 * x;

2 * x + 2 * x = 11 + 8;

4 * x = 19;

x = 19/4;

x = 16/4 + ;

x = 4 .   

2) 12 * x^2 + 17 * x 14 = 0;

D = 17^2 4 * 12 * (-14) = 17 * 17 + 48 * 14 = 289 + 672 = 961 = 31^2;

x1 = (-17 + 31)*(2 * 12) = (20 6)/24 = 14/24 = 7/12;

x2 = (-17 31)/(2 * 12) = -48/24 = -2.