In the root position of G-dominant seventh chord, the bass note is G, the root of the seventh chord.
In figured bass, a root-position triad has no symbol, while a root-position seventh chord is notated with a "7".
According to The American History and Encyclopedia of Music:Inversions are not restricted to the same number of tones as the original chord, nor to any fixed order of tones except with regard to the interval between the root, or its octave, and the bass note, hence, great variety results.
[1]Note that any voicing above the bass is allowed.
A root position, or uninverted, chord must have the root chord factor in the bass, but it may have any arrangement of the third and fifth above that, including doubled notes, compound intervals, and omission (C-E-G, C-E-G-E', C-G'-E'', etc.)