Answer:
Step-by-step explanation:
8. 4p^2 - 8q^2 + 3r^2 + 3p^2 + 5q^2 - 10r^2
7p^2 - 3q^2 - 7r^2
9. 2x^3 - 4x^2 + 3x + 6x^2 - 12x + 9
2x^3 + 2x^2 - 9x + 9
