The expression provided is $(x^3)^4$. To simplify it, we can use the power of a power property of exponents, which states that $(a^m)^n = a^{m \cdot n}$.

Applying this rule:

$(x^3)^4 = x^{3 \cdot 4} = x^{12}$

So, the simplified form of the expression is:

$x^{12}$

Would you like more details on exponent rules or have any questions? Here are 5 related questions for further practice:

1. How would you simplify $(x^2)^5$?
2. What is the simplified form of $(y^4)^3$?
3. Can you explain the difference between the product of powers and the power of a power rule?
4. How would you simplify the expression $(x^5)^3 \cdot (x^2)^2$?
5. What is the expanded form of $x^{12}$?

Tip: When dealing with exponents, remember that multiplying exponents occurs only when you have a power raised to another power.