11. Calculează: a) (3 + 2y) (x2 – 2xy + 4y2- 8y: b) (x – 2) (x3 +2x2 +4x+8) - (x-2)(x+2)(x2 + 4); c) (2 - 3) (2 – 2) + (x + 4) (1 - 1) - (2x - 1) (x - 2); ​