f ( t ) = 8 * [ t * e^{-0.4*t} ]
Nach der Produktregel
u = t
u ´= 1
v = e^{-0.4*t}
v ´ = e^{-0.4*t} * (-0.4 )
( u * v )´= u´ * v + u * v´
1 * e^{-0.4*t} + t * e^{-0.4*t} * (-0.4 )
e^{-0.4*t} * ( 1 + t * (-0.4 ))
f ´( t ) = 8 * [ e^{-0.4*t} * ( 1 - 0.4 * t ]