[tex]\it 4\sqrt6=\sqrt{4^2\cdot6}=\sqrt{16\cdot6}=\sqrt{96}<\sqrt{100}=10 \Rightarrow 4\sqrt6<10 \Rightarrow \\ \\ \Rightarrow 4\sqrt6-10<0 \Rightarrow a=|4\sqrt6-10|=-4\sqrt6+10=10-4\sqrt6[/tex]
[tex]\it m_g=\sqrt{a\cdot b}=\sqrt{(10-4\sqrt6)(10+4\sqrt6)}=\\ \\ =\sqrt{10^2-(4\sqrt6)^2}=\sqrt{100-96}=\sqrt4=2[/tex]
