Show off your theory chops with my weekly challenge! You’ll find a new question here every Monday. Please comment to post your reply.
This Week’s Challenge:
When approaching a cadence, you’ll very often see a I chord in second inversion (I 6/4). It’s called cadential 6/4, and you can see it below in this excerpt from Scott Joplin’s Maple Leaf Rag. What harmony does this chord really imply, and why does it function this way?

Post your reply and come back Friday, March 11th for the answer!
ANSWER for 3/7/22
A triad sounds most unstable in second inversion. This is because the bottom interval is a perfect fourth, which is technically treated as a dissonance because of its tendency to resolve down to a major 3rd. So near a cadence, a I 6/4 chord really sounds like a V chord with a couple of suspensions above the bass. The 4th, in particular, wants to resolve down to the 3rd of the V chord. So, near a cadence, a I 6/4 chord is really a delayed dominant, or, put differently, an expansion of the dominant harmony. You can also think of I 6/4 as a dominant that hasn’t put the other shoe in yet!

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