Respuesta :

Answer:

Below.

Step-by-step explanation:

81 - x^4        Treat as the difference of 2 squares:

= (9 - x^2)(9 + x^2)

We can further factor the 9 - x^2   (difference of 2 squares)

= (3 - x)(3 + x)(9 + x^2).

9 + x^2 can't be factored.