Question

What are the types of roots of the equation below?

x 4 - 81 = 0



Four complex


Two complex and two real


Four real

Answer 1

four real

Answer 2

\[x^4-81=0\\(x^2-9)(x^2+9)=0\\x^2=9 ,x^2=-9\\ \rightarrow x^2=9 \\x=\pm3\\x^=-9 \rightarrow x=\pm 3i\]

Answer 3

(x^2-9)(x^2+9)=0

Answer 4

2 real and 2 complex