The given expression is $9\sqrt{3} + 2\sqrt{3}$.

Since both terms involve $\sqrt{3}$, you can combine them by adding the coefficients of $\sqrt{3}$. The operation is similar to adding like terms in algebra:

$9\sqrt{3} + 2\sqrt{3} = (9 + 2)\sqrt{3} = 11\sqrt{3}$

So, the answer in simplest form is:

$\boxed{11\sqrt{3}}$

Would you like a further breakdown or have any additional questions?

Here are some related questions to consider:

1. How do you simplify expressions involving square roots?
2. What happens if the square roots are different, like $\sqrt{2}$ and $\sqrt{3}$?
3. How can you rationalize a denominator if it involves a square root?
4. How would you handle subtraction with square roots like $9\sqrt{3} - 2\sqrt{3}$?
5. Can you simplify an expression like $5\sqrt{12} + 3\sqrt{3}$?

Tip: When adding or subtracting square roots, make sure they are the same radical (like $\sqrt{3}$) before combining.