4. Решите уравнение: (5x − 1)(x + 2) + 3(x − 4)(x + 4) = 2(2x + 3)2 − 8.

5x^2 + 10x - x - 2 + 3(x^2 - 16) = 2(4x^2 + 12x + 9) - 8 

5x^2 + 9x - 2 + 3x^2 - 48 = 8x^2 + 24x + 18 - 8 

8x^2 + 9x - 50 = 8x^2 + 24x + 10

9x - 50 = 24x + 10

9x - 24x = 50 + 10

- 15x = 60

x = - 60/15

x =4