Answer:
1. [tex]12xz^{2} - 18yz^{2} + 30z^{3}[/tex]
2. [tex]7x^{5}+7x^{4} - 21x^{2}[/tex]
3. [tex]100x^{5}y^{4}[/tex]
4. [tex]12x^{5}-6x^{4} +9x^{2}[/tex]
5. [tex]x^{2} - 8x + xy - 8y[/tex]
6. (a+3) x (a+6) = [tex]a^{2} + 9a + 18[/tex]
7. [tex]3(3ab^{2} + 1)[/tex]
8. [tex]a^{3} (a^{8} + 1)[/tex]
