Hàm số $f(x)=\left(x^2+2x\right)\mathrm{e}^{-x}$ có đạo hàm
$f'(x)=\left(x^2+4x+2\right)\mathrm{e}^{-x}$ | |
$f'(x)=\left(2x+2\right)\mathrm{e}^{-x}$ | |
$f'(x)=\left(-2x+2\right)\mathrm{e}^{-x}$ | |
$f'(x)=\left(-x^2+2\right)\mathrm{e}^{-x}$ |
Chọn phương án D.
Ta có $\begin{aligned}[t]
f'(x)&=(2x+2)\mathrm{e}^{-x}-\left(x^2+2x\right)\mathrm{e}^{-x}\\
&=\left(-x^2+2\right)\mathrm{e}^{-x}.
\end{aligned}$