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As you can see, the extended penatatonic scale that begins on the 6th string intersects the first three positions of the pentatonic scale.
The first note of the extended pentatonic scale is the MINOR TONIC. In this case--an A note, so therefore, the scale is being played in the key of Am.
The second note of the extended pentatonic scale is the MAJOR TONIC. In this case--a C note, so therefore, the scale is also being played in the key of C.
Wherever you apply this scale along the fretboard, your tonic locations will not change. And this is how we understand how to play in whatever key we wish. With this lesson's many examples, I intend to demonstrate this concept. I intend for you to walk away with an understanding of how to apply the extended pentatonic scales in any key.