a) $\displaystyle\int(x^2 - 3x +1)dx$
$=\displaystyle\int x^2dx - 3\displaystyle\int xdx + \displaystyle\int dx$
$= \dfrac{x^3}{3} - \dfrac{3x^2}{2} + x + C$
b) $\displaystyle\int\dfrac{x^3 + 3x^2 - x - 1}{x}dx$
$=\displaystyle\int\left(x^2 + 3x - 1 -\dfrac1x\right)dx$
$=\displaystyle\int x^2dx + 3\displaystyle\int xdx - \displaystyle\int - \displaystyle\int\dfrac{1}{x}dx$
$=\dfrac{x^3}{3} +\dfrac{3x^2}{2} - x -\ln|x| + C$
c) $\displaystyle\int(2^x + 2x -5)dx$
$=\displaystyle\int 2^xdx + 2\displaystyle\int xdx - 5\displaystyle\int dx$
$=\dfrac{2^x}{\ln 2} + x^2 - 5x + C$
