\solution{12.1}{corriges/exercice-12.1.tex}
\solution{12.2}{corriges/exercice-12.2.tex}
\solution{12.3}{corriges/exercice-12.3.tex}
\solution{12.4}{corriges/exercice-12.4.tex}
\solution{12.5}{corriges/exercice-12.5.tex}
\solution{12.6}{corriges/exercice-12.6.tex}
\solution{12.7}{corriges/exercice-12.7.tex}
\solution{12.8}{corriges/exercice-12.8.tex}