[tex]\it m_a = \dfrac{a+b+c}{3} \Rightarrow 7\sqrt3=\dfrac{-4+6\sqrt3+14\sqrt3+c}{3} \Rightarrow 21\sqrt3=-4+20\sqrt3+c\\ \\ \\ \Rightarrow c=21\sqrt3+4-20\sqrt3 \Rightarrow c=4+\sqrt3[/tex]
Media aritmetică a numerelor a și b este:
[tex]\it \dfrac{a+b}{2} =\dfrac{-4+6\sqrt3+14\sqrt3}{2} =\dfrac{-4+20\sqrt3}{2} =\dfrac{2(-2+10\sqrt3)}{2}=-2+10\sqrt3[/tex]
