If 5 + 6i is a root of the polynomial function f (x), which of the following must also be a root of f (x) ?

A. - 5 - 6iB. 5 - 6iC. 6 - 5iD. 6 + 5i

5 - 6i must also be a root. to get an imaginary number, you take the square root of a negative value. square roots give you the positive and negative outcome.

consider the quadratic formula: - b ± √ (b^2 + 4ac) / 2a

the ± symbol shows that your roots include the positive and negative version.