Упростите выражение 1) (a+2) * (a-3) - (4-a) * (a+4) 2) (5-2x) * (5+2x) - (3-2x) * (4-2x) Решите уравнения. 1) 4x * (7+9x) - (6x+5) * (6x-5) = 39 2) (x-8) * (x+10) - (x+7) * (x-7) = 5x - 31

1) (a + 2) * (a - 3) - (4 - a) * (a + 4) = a^2 - 3a + 2a - 6 - (16 - a^2) = a^2 - 3a + 2a - 6 - 16 + a^2 = 2a^2 - a - 22.

2) (5 - 2x) * (5 + 2x) - (3 - 2x) * (4 - 2x) = 25 - 4x^2 - (12 - 6x - 8x + 4x^2) = 25 - 4x^2 - 12 + 6x + 8x - 4x^2 = - 8x^2 - 14x + 13.

1) 4x * (7 + 9x) - (6x + 5) * (6x - 5) = 39;

28x + 36X^2 - (36x^2 - 25) = 39;

28x + 36X^2 - 36x^2 + 25 = 39;

28x + 25 = 39;

28x = 39 - 25;

28x = 14;

x = 14/28;

x = 1/2;

x = 0,5

Ответ. 0,5.

2) (x - 8) * (x + 10) - (x + 7) * (x - 7) = 5x - 31;

x^2 + 10x - 8x - 80 - (x^2 - 49) = 5x - 31;

x^2 + 10x - 8x - 80 - x^2 + 49 = 5x - 31;

2x - 80 + 49 = 5x - 31;

2x - 5x = - 31 + 80 - 49;

- 3x = 0;

x = 0.

Ответ. 0.