Which component is explicitly included in the generalized mathematical expression of Kepler's Third Law modified by Newtonian mechanics?

Answer

The universal gravitational constant ($G$).

Newton modified Kepler's geometry by incorporating the gravitational law, resulting in a proportionality constant that explicitly includes $G$ and the masses of both objects ($M_1 + M_2$).

Which component is explicitly included in the generalized mathematical expression of Kepler's Third Law modified by Newtonian mechanics?
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