Evaluate the definite integrals

a) $\displaystyle\int_{1}^{9} \dfrac{1}{x} \, dx =$

b) $\displaystyle\int_{1}^{8} \dfrac{1}{x^2} \, dx =$

c) $\displaystyle\int_{1}^{9} \dfrac{1}{x^{3}} \, dx =$

d) $\displaystyle\int_{0}^{4} x^2 \, dx =$

e) $\displaystyle\int_{0}^{1} x^{75} \, dx =$