Anzuwenden ist die Produktregel
u = 1020 - 40t
u´= -40
v = e^{1/10*t} = e^{0.1*t}
v´ = e^{1/10*t} * (1/10) = e^{0.1*t} * 0.1
( u * v ) ´ = u´ * v + u * v´
f(t)=(1020 - 40t) x e1/10t
f ´( t ) = -40 * e^{0.1*t} + ( 1020 - 40t ) * e^{0.1*t} * 0.1
f ´( t ) = e^{0.1*t} * ( -40 + 102 - 4t )
f ´( t ) = e^{0.1*t} * ( 62 - 4t )