\[\sqrt{\left( 5 - \sqrt{7} \right)^{2}} + \sqrt{\left( 2 - \sqrt{7} \right)^{2}} =\]
\[= \left| 5 - \sqrt{7} \right| + \left| 2 - \sqrt{7} \right| =\]
\[= 5 - \sqrt{7} + \sqrt{7} - 2 = 3.\]