Answer:
1. -21a^6 b^4
2. 32a^7 b^4
3. -35x^7y^8+45x^3y^2
4. 24m^3n+8mn^3
5. 18a^2+9a-54
6. 30a^2-23a+3
7. 28x^4+72x^2+32
8. 4a^2-18a^3+8a^2-32a-18
9. 3z^5+5x^4-28x^3-4x-16
10. 30x^4-22x^3-46x^2+68x-28
