Let's simplify the given expression:

$a^2b^2 + 3a^2b^2 - a^2b^2$

We can combine like terms, where the terms with $a^2b^2$ can be added or subtracted:

$(1a^2b^2 + 3a^2b^2 - 1a^2b^2)$

This simplifies to:

$(1 + 3 - 1) a^2b^2 = 3a^2b^2$

So, the simplified expression is:

$3a^2b^2$

Would you like any further clarification on this?

Here are 5 related questions for you:

1. How do you combine like terms with different powers?
2. What are some real-life applications of expressions like $a^2b^2$?
3. Can you simplify expressions with variables raised to different powers?
4. How would you factor $3a^2b^2$?
5. What happens when you multiply terms with exponents, such as $a^2 \times b^2$?

Tip: Always look for common factors or terms that have the same variable powers when combining like terms!