### Instruction: Simplify the following expression: $\sqrt{28 + \sqrt{1296}}$.### Response: To simplify a square root expression, I need to look for perfect squares inside the radical.
I notice that 1296 is a perfect square, since it is equal to 36 squared.
So I can rewrite the expression as $\sqrt{28 + \sqrt{1296}} = \sqrt{28 + 36}$.
Now I need to simplify the sum inside the square root.
28 + 36 is equal to 64, which is another perfect square.
So I can rewrite the expression again as $\sqrt{28 + \sqrt{1296}} = \sqrt{28 + 36} = \sqrt{64}$.
Finally, I can take the square root of 64, which is 8.
So the simplified expression is 8.