Which statement about inverse matrices is true?
a)an inverse matrix is always a square matrix
b)an inverse matrix is never a square matrix
c)the determinant of an inverse matrix is always zero
d)there always exist a square matrix a^-1 for which aa^-1= i

 Option 'a'and 'd' are true.

Step-by-step explanation:

Inverse matrices are those matrices for their always exist a square matrix such that

Matrix should have non zero determinant for getting inverse of it.

An inverse matrix should be square matrix.

Inverse of matrix can be calculated by two approaches:

1) Adjoint method

2) Row/Column elementary method

Hence, Option 'a'and 'd' are true.