If f(x)=∫xa t3et dt, then ddxf(x)= [MP PET 1989]
None of these
f(x)=∫xa t3et dt=∫0at3.et dt+∫x0t3etdt ⇒df(x)dx=ddx(∫0a t3.et dt)+ddx(∫x0t3.et dt)=x3ex