The expression you provided is:

$1 + (2 + t)e^{-t}$

This is a mathematical expression involving an exponential term. Would you like me to simplify, differentiate, or perform another operation on it? Let me know how you'd like to proceed!

Here are some questions to further explore the topic:

1. How do you differentiate the expression $1 + (2 + t)e^{-t}$?
2. How do you find the integral of the expression $1 + (2 + t)e^{-t}$?
3. What are the behavior and limits of the function as $t \to \infty$ and $t \to -\infty$?
4. How would you find the value of the expression for a specific value of $t$?
5. Can this expression be used in a differential equation?

Tip: When dealing with exponential functions like $e^{-t}$, remember that their rate of change is directly proportional to their current value, and it decays as $t$ increases.