INT$2.$ Compute the following definite integrals.

a$.){\displaystyle \underset{0}{\overset{2}{}}}6x^2-2x+6dx$

b$.){\displaystyle \underset{0}{\overset{2}{}}}se{c}^2(x)dx$

c$.){\displaystyle \underset{-1}{\overset{1}{}}}\frac{1}{x}+e^{x}dx$