The live lesson on the circle of fifths was fantastic (as all live lessons I´ve seen so far are – I feel like the topics are representing what is going on in the forum and Matt is just such an excellent teacher).
After reading so much on theory here and there and anywhere this lesson just gave me a kickstart. Thank you! After that I looked into chord inversions and read (again) through the “How to Write a Song on the Ukulele -…” pdf book (and finally felt like I started understanding something).
Reading that and having just looked at chord inversions I wondered how you can play a chord without using all the notes in it?!
For example “Day Dreaming” bar 12 is a G. For a G one needs a G-B-D. But in that bar you only play G and B. What happened to the D? Does it feel left out because it isn´t played even though the chord of G needs to have a D in it? How can one hear that it is a G chord and not some other chord that has a G and B in it?
As to your question: 5 is expendable. The 3rd is what determines the quality of the chord. So in the example above, 1 (G) and 3 (B) is enough information to discern a major 3rd interval which alludes to a major triad.