Answer: 3, -3, 3i, -3i
Step-by-step explanation:
[tex]x^4-81=0\\\\Factor:\\(x^2-9)(x^2+9)=0\\(x-3)(x+3)(x^2+9)=0\\\\\text{Apply the Zero Product Property:}\\x-3=0\qquad x+3=0\qquad x^2+9=0\\\boxed{x=3}\qquad \qquad \boxed{x=-3}\qquad \quad x^2=-9\\.\qquad \qquad \qquad \qquad \qquad \qquad x=\sqrt{-9}\\.\qquad \qquad \qquad \qquad \qquad \qquad \boxed{x=\pm 3i}[/tex]
