1. **State the problem:** Simplify or analyze the expression $-xe^{-x}$. 2. **Understand the components:** The expression consists of a product of $-x$ and the exponential function $e^{-x}$. 3. **Recall the exponential function:** $e^{-x}$ means $\frac{1}{e^x}$, which decreases as $x$ increases. 4. **No further simplification is possible:** The expression $-xe^{-x}$ is already in a simplified form. 5. **Interpretation:** For positive $x$, $-x$ is negative and $e^{-x}$ is positive, so the product is negative. For negative $x$, $-x$ is positive and $e^{-x}$ is greater than 1, so the product is positive. 6. **Summary:** The function $f(x) = -xe^{-x}$ is negative for $x>0$ and positive for $x<0$, and equals zero at $x=0$.