The expression you provided is a summation notation, given by:

$\sum_{i=3}^{n} (x_i + 10)^2$

This means you are summing the squared values of $(x_i + 10)$ from $i = 3$ to $i = n$, where $x_i$ represents the elements of some sequence or function.

The sum is expanded as follows:

$(x_3 + 10)^2 + (x_4 + 10)^2 + \dots + (x_n + 10)^2$

To calculate the result, you would need to know the values of $x_i$ for each index $i$ from 3 to $n$, as well as the upper limit $n$.

Would you like to clarify the values of $x_i$ and $n$, or should I assist further in another way?

Here are some related questions to expand upon this:

1. What is the value of $n$ in your problem?
2. Do you know the specific values for each $x_i$?
3. Should the summation be simplified symbolically without specific values of $x_i$?
4. Would you like to generalize this formula for a sequence of $x_i$?
5. Are you working with specific conditions or constraints for $x_i$?

Tip: Summation notation is useful to represent large sums concisely, especially when dealing with sequences or patterns in data.