
The given polynomial 81 − 49n⁴ is not a difference of two squares because −49n⁴ is not a perfect square.
We can see that 81 is a perfect square because it is equal to 9². However, 49n⁴ is not a perfect square because it can't be written as the square of a single term.
Therefore, we cannot factor 81 − 49n⁴ into the difference of two squares.