The 7th chord is based on the 1st (Root) - 3rd - 5th & b7th notes of a major scale. Inversions change the order of the notes by playing a different note as the lowest note of the chord. The chord symbols are written using a slash (/) such as C7/E which means to play a C7 chord with the E note as the lowest note in the chord. These chord symbols are common to other instruments such as keyboards.
