documentclass[xcolor=dvipsnames]{beamer}
      usecolortheme[named=blue]{structure}
         usepackage[tikz]{bclogo}
      %------------------------AtBeginSubsection[]----------------------
     AtBeginSubsection[]{
       begin{frame}<beamer>[noframenumbering,plain]{Outline}
     transsplitverticalout
    tableofcontents[currentsection,currentsubsection]
       end{frame}
      }

   usetheme{Madrid}


     begin{document}

       begin{frame}{}
        begin{bclogo}[arrondi=0.1, logo=bcquestion, couleurBarre=Maroon]
              {Question}
          Why
          $$r_e(mathbf{T})geq r(mathbf{T}) ;?$$
          end{bclogo}
        end{frame}

     end{document}