Chords going well with pentatonic scale and blues scale?

Question

Let's say I want to improvise (create a solo) on the pentatonic scale A C D E G:

E||---------------------5-8-|
B||-----------------5-8-----|
G||-------------5-7---------|
D||---------5-7-------------|
A||-----5-7-----------------|
E||-5-8---------------------|

What chords should my friend play along so it would make sense?

What about if I improvise on the blues scale A C D Eb E G:

E||-------------------------5-8-|
B||---------------------5-8-----|
G||---------------5-7-8---------|
D||-----------5-7---------------|
A||-----5-6-7-------------------|
E||-5-8-------------------------|

I'm sure there are a bunch of chords, but what would be some standard/usual ones for beginners to practice?

Also, I often play this scale:

E||------------------------|
B||------------------------|
G||-----------------7-9----|
D||-----------5-7-9--------|
A||-------5-7--------------|
E||-3-5-7------------------|

What is this scale called and what would be suitable chords to play along?

Answer 1

Simply use the chords whose roots are the note names you play.The scale is Am pent., and Am blues. Those notes work fine over both major and minor chords (and of course 7th s in blues!). I'm not saying you only play A while the chord is A, etc, that would sound not-so-good!

So, with A D and E notes and chords, that would put you in A - maj or min - try both. The C and G are then said to be borrowed from the parallel key. (A / Am).

Bear in mind that there are two pent scales, and two blues scales. Yours are both minor. however, the last one, whiolst containing the same notes as Em pent., is actually G maj. pent., starting and finishing on - G!