Find the maximum value of f(x)=x3e−xf(x) = x^3 e^{-x}f(x)=x3e−x on [0,∞)[0, \infty)[0,∞).
27e−327e^{-3}27e−3
e−3e^{-3}e−3
3e−13e^{-1}3e−1
e−1e^{-1}e−1