To compute $\int_{2}^{7}\int_{3}^{7} \left( \frac{10xy}{\sqrt{x^{2}+y^{2}+6}} \right) dxdy$ you do the u substitution:
u =
du =

$\int_{2}^{7}\int_{3}^{7} \left( \frac{10xy}{\sqrt{x^{2}+y^{2}+6}} \right) dxdy =$