In a major key, the seventh of the dominant seventh chord usually resolves:

The answer to this question is "Major ninth on the dominant seventh chord V7 usually resolves Appoggiatura or the down by step going to the root of the dominant seventh". This V7 is frequently deleting the ninth functions on the chords as an upward resolving the issue and problem of Appoggiatura which is usually located on the third chord.  

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