What is the seventh chord associated with a major chord and a minor seventh?

The seventh chord associated with a major chord and a minor seventh is the dominant 7th chord. This chord is constructed by taking a major triad and adding a minor seventh above the root.

In terms of construction, if you have a major chord built on a root note, for instance, C major (C-E-G), and you add a B♭, which is a minor seventh above C, you end up with the notes C-E-G-B♭. This combination creates the characteristic sound of a dominant 7th chord, which leads strongly to the tonic chord in harmonic progressions.

In musical contexts, the dominant 7th chord plays a crucial role in establishing tension that resolves to the tonic, making it integral to the structure of tonal music. The presence of the minor seventh, along with the major triad, is what defines it as a dominant 7th chord, differentiating it from other seventh chords like major 7th or minor 7th, which have different qualities and structures.