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Calculer l’inverse de : \[\left( \begin{array}{llll} 1 & a & ... & a \\ 0 & 1 & a & ... \\ ... & 0 & 1 & a \\ 0 & ... & 0 & 1 \end{array} \right) ,a\in {\Rr}.\]
Calculer l’inverse de : \[\left( \begin{array}{llll} 1 & a & ... & a \\ 0 & 1 & a & ... \\ ... & 0 & 1 & a \\ 0 & ... & 0 & 1 \end{array} \right) ,a\in {\Rr}.\]