1
Calculer \(\left| \begin{array}{cccc} a&b&\ldots&b\\ b&a&\ddots&\vdots\\ \vdots&\ddots&\ddots&b\\ b&\ldots&b&a \end{array} \right|\).
Calculer \(\left| \begin{array}{cccc} a&b&\ldots&b\\ b&a&\ddots&\vdots\\ \vdots&\ddots&\ddots&b\\ b&\ldots&b&a \end{array} \right|\).