Determine whether the expressions are equivalent or not.

? Equivalent Not Equivalent  1. $(x+3)^2$ and $\sqrt{x^4 + 81}$

? Equivalent Not Equivalent  2. $x^2 + 9$ and $\sqrt{x^4 + 81}$

? Equivalent Not Equivalent  3. $(x+3)^2$ and $x^2 + 9$