How to play a Bmaj7 chord on Accordion

What key is Bmaj7 in music? bmaj7 Quick lesson on how to play the Bmaj7 Chord on guitar The strings I refer to as ebmaj7 Chord name Bmaj7 is an abbreviation for B major seventh A less common abbreviation is BM7 A third system is the triangle symbol: B△7

bbmaj7 Bmaj7 chord The A major seventh chord is a tetrad with formula 1 – 3 – 5