A matrix is invertible if and only if it has a nonzero determinant. Only square matrices (''n'' x ''n'') are invertible.
A matrix is invertible if and only if it has a nonzero determinant. Only square matrices (''n'' x ''n'') are invertible.
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It can be shown that, for any invertible matrix ''A'', there is only one matrix ''B'' such that ''AB'' = I; this unique matrix is called the [[inverse matrix]] of ''A'', and represented as ''A<sup>-1</sup>''.