Evaluate the definite integrals

a) $\displaystyle\int_{3}^{5} (6 x^2 - 6 x + 8) \, dx =$

b) $\displaystyle\int_{3}^{6} (x - 4)^2 \, dx =$

c) $\displaystyle\int_{-1}^{1} (x^{5} - x^{9}) \, dx =$