The given polynomial 81a² − 25z⁶ is not a difference of two squares because −25z⁶ is not a perfect square.
We can see that 81a² is a perfect square because it is equal to (9a)². However, 25z⁶ is not a perfect square because it can't be written as the square of a single term.
Therefore, we cannot factor 81a² − 25z⁶ into the difference of two squares.
