a) (5x + 7) x (2x + 4 + 3x +3) - (4x - 3) x (3x + 9 + x - 6) =
(5x + 7)(5x + 7) - (4x - 3)(4x - 3) =
[(5x+7)+(4x-3)][(5x+7)-(4x-3)] =
(9x + 4)(x + 10) =
9[tex] x^{2} [/tex] + 94x + 40
b) (x + 1)(5x + 1 - 2x - 8) - (3x + 2)(7x + 14 - 4x - 12) =
(x + 1)(3x - 7) - (3x + 2)(3x + 2) =
3[tex] x^{2} [/tex] - 4x - 7 - 9[tex] x^{2} [/tex] - 12x - 4 =
-6[tex] x^{2} [/tex] -16x - 11