im stuck w/ this integral:
$\displaystyle \int \frac{-(x+1)}{x^2+x+1}dx$
$\displaystyle -\int\frac{x}{x^2+x+1}dx -\frac{2}{\sqrt{3}}\arctan{\frac{2x-1}{\sqrt{3}}}$
The integral can be rewritten as follows:
$\displaystyle - \int {\frac{{x + 1}}
{{x^2 + x + 1}}~dx} = - \frac{1}
{2}\left[ {\ln (x^2 + x + 1) + \int {\frac{1}
{{\left( {x + \dfrac{1}
{2}} \right)^2 + \left( {\dfrac{{\sqrt 3 }}
{2}} \right)^2 }}~dx} } \right]$
Sure you can make it from there.