a)
5(x + 1) + 7(x - 1) - 3(x^2 + x) = 5x + 5 + 7x - 7 - 3x^2 - 3x = - 3x^2 + 9x - 2
= - 3x(x-3)-2
b)
2(3x^2 - 3) + (2x + 1)(2 - x) = 6x^2 - 6 + 4x - 2x^2 + 2 - x = 4x^2 + 3x - 4
c)
7x (\frac{1}{7} x - \frac{6}{7}) - \frac{1}{5}(5x + 5)(x - 1) = x^2 - 6x - \frac{1}{5}(5x^2 - 5x + 5x - 5) =
x^2 - 6x - \frac{1}{5}(5x^5 - 5)= x^2 - 6x - x^2 + 1 = 6x + 1
d)
(5x - 2)(3x - 1) - 3(x - 1)(2x + 3) =15x^2 - 5x - 6x + 2 -3(2x^2 + 3x -2x - 3)=
15x^2 - 5x - 6x + 2 - 6x^2 - 9x + 6x + 9 = 9x^2 - 14x + 11