$=\int _{-1}^{-6}-\frac{2-\sqrt{-u+3}}{u}du$
$=-\int _{-6}^{-1}-\frac{2-\sqrt{-u+3}}{u}du$
$=-(-\int _{-6}^{-1}\frac{2-\sqrt{-u+3}}{u}du)$
$=-(-\int _{-6}^{-1}\frac{2}{u}-\frac{\sqrt{-u+3}}{u}du)$
$=-(-(\int _{-6}^{-1}\frac{2}{u}du-\int _{-6}^{-1}\frac{\sqrt{-u+3}}{u}du))$
$=-(-(-2\ln(6)-(\sqrt{3}\ln(2-\sqrt{3})-2)))$
$=-2\ln(6)-\sqrt{3}\ln(2-\sqrt{3})+2$