1. **State the problem:** Simplify the expression $4x^2$. 2. **Understand the expression:** The expression $4x^2$ means 4 times $x$ squared. 3. **No further simplification is possible:** Since $4x^2$ is already in its simplest form, there are no like terms to combine or factors to simplify. 4. **Final answer:** The simplified expression is $4x^2$.