Hey online, good to see you again. Step 1: Identify the integral expression. The integral to evaluate is given as: $$ \int e^{-t} \, dx $$ Step 2: Determine the variable of integration. The differential $dx$ indicates that the integration is with respect to $x$. Step 3: Treat $e^{-t}$ as a constant. Since $t$ is not the variable of integration $x$, $e^{-t}$ is considered a constant during this integration. Step 4: Apply the integration rule for a constant. The integral of a constant $k$ with respect to $x$ is $kx + C$. In this case, $k = e^{-t}$. $$ \int e^{-t} \, dx = e^{-t} \int 1 \, dx = e^{-t} \cdot x + C $$ The final answer is $\boxed{x e^{-t} + C}$. Send me the next one 📸