changed: -integrate((x^2-1)*arctan(a*x),x) integrate((x^2-1)*atan(a*x),x)
integrate((x^2-1)*atan(a*x),x)
![\label{eq1}{\left(
\begin{array}{@{}l}
\displaystyle
{{\left({3 \ {{a}^{2}}}+ 1 \right)}\ {\log \left({{{{a}^{2}}\ {{x}^{2}}}+ 1}\right)}}+
\
\
\displaystyle
{{\left({2 \ {{a}^{3}}\ {{x}^{3}}}-{6 \ {{a}^{3}}\ x}\right)}\ {\arctan \left({a \ x}\right)}}-{{{a}^{2}}\ {{x}^{2}}}](images/4880804735746490937-16.0px.png "\label{eq1}{\left(
\begin{array}{@{}l}
\displaystyle
{{\left({3 \ {{a}^{2}}}+ 1 \right)}\ {\log \left({{{{a}^{2}}\ {{x}^{2}}}+ 1}\right)}}+
\
\
\displaystyle
{{\left({2 \ {{a}^{3}}\ {{x}^{3}}}-{6 \ {{a}^{3}}\ x}\right)}\ {\arctan \left({a \ x}\right)}}-{{{a}^{2}}\ {{x}^{2}}}")