\[2R_{G}\left(x+\lambda,y+\lambda,z+\lambda\right)+2R_{G}\left(x+\mu,y+\mu,z+\mu%
\right)=2R_{G}\left(x,y,z\right)+\lambda R_{F}\left(x+\lambda,y+\lambda,z+%
\lambda\right)+\mu R_{F}\left(x+\mu,y+\mu,z+\mu\right)+\sqrt{\lambda+\mu+x+y+z}.\]