What are the types of roots of the equation below? x^4 - 81 = 0

a- four complex
b- two complex and two real
c- four real

Your answer is B, two complex roots and two real roots.

By factoring the original equation(which is a difference of two squares), you get:


Because first root is also a difference of two squares, it factors into x - 3 and x +3, your two real roots.
When you factor the second root, the roots are x - 3i and x + 3i.

To prove this, let's multiply them back together:


We reached the equation we started with, so that means that the roots are:
x + 3,
x - 3,
x + 3i, and
x - 3i,
two of which are real and two are complex.

The answer that i got was 8/3