1. Multiply: $(3x - 1)(9x^2 + 3x + 1) = \_\_\_$
2. Multiply: $s^2t^2(2s + t)(3s - t) = \_\_\_$
3. Multiply: $4a(a - 1)(a + 5) = \_\_\_$
4. Compute the product: $5(2x + 1)(2x - 1) = \_\_\_$
5. Multiply: $(x - 2)(x^2 - 3x + 2) = \_\_\_$
6. Compute the product: $-3(x + 4)(x - 1) = \_\_\_$
7. Compute the product: $2(3x - 1)(x - 3) = \_\_\_$
8. Compute the product: $-(4x + 3)(x - 2) = \_\_\_$
9. Multiply: $(2x - a)(x - 3a) = \_\_\_$
10. Let $f(x) = 3x^2 - 2x + 1$ and $g(x) = x^2 + 5x - 4$. Find the sum function $(f+g)(x)$. Your answer should be a polynomial in the form $ax^2+bx+c$. ___