Répondre :

f(x)=(x-4)e^(-0.25x+5)
f'(x)=1*exp(-0,25x+5)+(x-4)*(-0,25)*exp(-0,25x+5)
      =(1-0,25x+1)*exp(-x/4+5)
      =(-x/4+2)*exp(-x/4+5)
f(x)=(x-4)e^(-0.25x+5)
f'(x)=1*exp(-0,25x+5)+(x-4)*(-0,25)*exp(-0,25x+5)
      =(1-0,25x+1)*exp(-x/4+5)
      =(-x/4+2)*exp(-x/4+5)