It is simply the 'inverse' of each element of your vector (so vectorization is implicit here). That's the only way way Mathcad can produce an answer that is not an error message.

The help on Matrix inverse is:

Matrix Inverse Operator

Keystroke: ^-1

This returns the inverse of a matrix. If M does not have an inverse, you'll see an appropriate error message.

Operands:

• M is a square matrix having an inverse.

Your multiplication A * A^-1 results in 3, because A has three elements.

The symbolic (Maple) processor complains that the matrix should be square...

Success!

Luc