I'm new to the bass and music theory in general although i have played guitar for the better part of my life. I have a question that has kind of stumped me... I've learned that the I, IV, and V chord are the most used chords in any key. However, I'm not sure why the major pentatonic removes the IV (4) from its scale. You would think the bassist would be playing root A whenever the A chord is being played by the guitarist example: the song "Lady Picture Show" by Stone Temple Pilots starts off with E, B, and A repeat for intro and verse. When creating my bass line I can't hit the root note of "A" bc its not in the E major pent scale. This seems off to me... You may say, "well just play the normal E major diatonic scale". I would agree with this, however, I've been told that the pent scales are really the go to scale when creating bass lines and soloing (guitar or bass). I do play guitar so perhaps I'm a little confused with the integration of the pent scale? Is the pent scale more for guitarist to improvise/play lead? Do I mostly use the diatonic scale when when playing a song like the one above? BOTTOM LINE: I just find it hard to believe that the pent scale is lauded as the "go-to" scale yet it removes the 4th which besides the Root and 5th is the most used chord progression. This has really been frustrating me lately!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Please give me some good insight so I don't go home and try to find the answer to this and it cuts into my precious bass playing time.