TeX source:

S S Q_{\text {condition }}=\mathrm{n}\left[\left(\mathrm{M}_{1}-G M\right)^{2}+\left(\mathrm{M}_{2}-G M\right)^{2}+\ldots+\left(\mathrm{M}_{\mathrm{k}}-G M\right)^{2}\right]