TeX source:

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