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Calculer les puissances de : \[\left( \begin{array}{ll} a & b \\ 0 & a \end{array} \right) ,\ \left( \begin{array}{ll} a & b \\ b & a \end{array} \right) ,\ \left( \begin{array}{lll} 1 & 1 & 1 \\ 0 & 1 & 1 \\ 0 & 0 & 1 \end{array} \right) .\]
Calculer les puissances de : \[\left( \begin{array}{ll} a & b \\ 0 & a \end{array} \right) ,\ \left( \begin{array}{ll} a & b \\ b & a \end{array} \right) ,\ \left( \begin{array}{lll} 1 & 1 & 1 \\ 0 & 1 & 1 \\ 0 & 0 & 1 \end{array} \right) .\]