Answer
$e^{-10x}\left( 1-10x\right) $
Work Step by Step
$\dfrac {d}{dx}\left( xe^{-10x}\right) =\left( \dfrac {d}{dx}\left( x\right) \right) \times e^{-10x}+\dfrac {d}{dx}\left( e^{-10x}\right) \times x=e^{-10x}-10\times e^{-10x}x=e^{-10x}\left( 1-10x\right) $
