Resolvam as operações de multiplicações de polinômios:

a) (2x3 – 3x2 + x – 1) + (5x3 + 6x2 – 7x + 3)
b) (– 8y2 – 12y + 5) + (7y2 – 8)
c) (2ax3 – 5a2x – 4by) + (5ax3 + 7a2x + 6by)
d) (a2 – b2) + (a2 – 3b2 – c) + (5c – 2b2 – a2)
e) (3y2 – 2y – 6) – (7y2 + 8y + 5)
f) (8x3 – 4x2 + 3x – 5) – (6x3 – 7x2 + 5x – 9)
g) (2x3 – 3x + 1) – (– 4x2 + 3)
h) (2x3 – 5x2 + 8x – 1) – (– 3x3 + 5x2 – 5x + 6)
i) (x2 – 5xy + y2) + (3x2 – 7xy + 3y2) – (4y2 – x2)