The domain of a function is determined by identifying any values of the variable $x$ that would make the function undefined. In the given expression:

$\frac{x^2 + 2x + 1}{x + 1}$

The denominator cannot be zero, since division by zero is undefined. So, we need to find when the denominator is zero:

$x + 1 = 0 \implies x = -1$

Thus, the function is undefined when $x = -1$.

Therefore, the domain of the expression is all real numbers except $x = -1$.

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Would you like more details or have any other questions?

Here are 5 questions related to this concept:

1. How do you determine the domain of a rational function?
2. What happens when a denominator is zero in a function?
3. Can this function be simplified further by factoring?
4. How do you find the domain of a polynomial function?
5. What is the range of a rational function like this one?

Tip: Always check for values that make the denominator zero when finding the domain of rational expressions.