math inverse matricies question?

Question

How do you know if a matricie has an inverse or not....???

Answer 1

1). First, only square matrices have inverses.
2). You can calculate the determinant of the matrix A.
If it is 0, A is singular and has no inverse.
3). You could reduce it by elementary row operations.
If you get a row of zeros, the matrix has no inverse.

Answer 2

I'm pretty sure all matricies have a inverse.

Answer 3

A matrix is invertible if its determinant is non-zero.
Just calculate its determinant.