Consider the indefinite integral 5x3+6x2+2x+4x4+1x2dx\displaystyle \int{\frac{{{5}{x}^{{3}}+{6}{x}^{{2}}+{2}{x}+{4}}}{{{x}^{{4}}+{1}{x}^{{2}}}}}{\left.{d}{x}\right.}
Then the integrand has partial fractions decomposition
ax2+bx+cx+dx2+1\displaystyle {\frac{{{a}}}{{{x}^{{2}}}}}+{\frac{{{b}}}{{{x}}}}+{\frac{{{c}{x}+{d}}}{{{x}^{{2}}+{1}}}}
where
a\displaystyle {a} =
b\displaystyle {b} =
c\displaystyle {c} =
d\displaystyle {d} =

Integrating term by term, we obtain that
5x3+6x2+2x+4x4+1x2dx=\displaystyle \int{\frac{{{5}{x}^{{3}}+{6}{x}^{{2}}+{2}{x}+{4}}}{{{x}^{{4}}+{1}{x}^{{2}}}}}{\left.{d}{x}\right.}=
  +C\displaystyle +{C}