Решите уравнение а) 6y+15) (2,4-0,8y) = 0 б) 2x - (5x-8) = 8+7x

а) (6 * y + 15) * (2, 4 - 0, 8 * y) = 0;

6 * y * 2, 4 + 6 * y * ( - 0, 8 * y) + 15 * 2, 4 + 15 * ( - 0, 8 * y) = 0;

6 * y * 2, 4 - 6 * y * 0, 8 * y + 15 * 2, 4 - 15 * 0, 8 * y = 0;

14, 4 * y - 4, 8 * y² + 36 - 12 * y = 0;

- 4, 8 * y² + 2, 4 * y + 36 = 0;

- 2 * y² + y + 15 = 0;

D = 1 - 4 * ( - 2) * 15 = 1 + 8 * 15 = 121 > 0;

y₁ = ( - 1 - 11) / (2 * ( - 2)) = - 12 / - 4 = 3;

y 2 = ( - 1 + 11) / (2 * ( - 2)) = 10 / - 4 = - 5/2 = - 2 1/2;

Ответ: 3; - 2 1/2.

б) 2 * x - (5 * x - 8) = 8 + 7 * x;

2 * x - 5 * x + 8 = 8 + 7 * x;

- 3 * x + 8 - 8 - 7 * x = 0;

- 10 * x = 0;

x = 0.

Ответ: 0.