[tex]a= \sqrt{( \sqrt{2} - \sqrt{5} )^2} =| \sqrt{2} - \sqrt{5} |= \sqrt{5} - \sqrt{2} \\ \\ \boxed{a= \sqrt{5} - \sqrt{2} } \\ \\ b= \sqrt{( \sqrt{2} + \sqrt{5} )^2} =| \sqrt{2} + \sqrt{5} |= \sqrt{5} + \sqrt{2} \\ \\ \boxed{b= \sqrt{5} + \sqrt{2} } \\ \\ m_g= \sqrt{( \sqrt{5} - \sqrt{2} )( \sqrt{5} + \sqrt{2} )} = \sqrt{5-2} = \sqrt{3} \\ \\ \boxed{m_g= \sqrt{3} }[/tex]