Exercise30.1

Use that the square matrix \(A\) has a \(QR\) factorisation to prove that

\begin{equation*} |\det(A)| \leq \prod_{j=1}^m \|a_j\|_2, \end{equation*}

where, as usual, \(a_j\) is column \(j\) of \(A\text{.}\)

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