Find $\int \frac{x^{4} dx}{(x-1)(x^{2}+1)}$

(A) We perform polynomial division to simplify the integrand:
$\frac{x^{4}}{(x-1)(x^{2}+1)} = \frac{x^{4}}{x^{3}-x^{2}+x-1} = (x+1) + \frac{1}{x^{3}-x^{2}+x-1} = (x+1) + \frac{1}{(x-1)(x^{2}+1)}$
Using partial fractions for $\frac{1}{(x-1)(x^{2}+1)}$:
$\frac{1}{(x-1)(x^{2}+1)} = \frac{A}{x-1} + \frac{Bx+C}{x^{2}+1}$
$1 = A(x^{2}+1) + (Bx+C)(x-1) = (A+B)x^{2} + (C-B)x + (A-C)$
Equating coefficients: $A+B=0$,$C-B=0$,$A-C=1$. Solving these gives $A=\frac{1}{2}$,$B=-\frac{1}{2}$,$C=-\frac{1}{2}$.
Substituting back:
$\int \frac{x^{4} dx}{(x-1)(x^{2}+1)} = \int (x+1) dx + \frac{1}{2} \int \frac{dx}{x-1} - \frac{1}{2} \int \frac{x dx}{x^{2}+1} - \frac{1}{2} \int \frac{dx}{x^{2}+1}$
$= \frac{x^{2}}{2} + x + \frac{1}{2} \ln|x-1| - \frac{1}{4} \ln(x^{2}+1) - \frac{1}{2} \tan^{-1}(x) + C$