If a polynomial function [tex]\( f(x) \)[/tex] has roots [tex]\(-8\)[/tex], [tex]\(1\)[/tex], and [tex]\(6i\)[/tex], what must also be a root of [tex]\( f(x) \)[/tex]?

A. [tex]\(-6\)[/tex]

B. [tex]\(-6i\)[/tex]

C. [tex]\(6 - i\)[/tex]

D. [tex]\(6\)[/tex]



Answer :

Given the roots of the polynomial function [tex]\( f(x) \)[/tex] are [tex]\( -8 \)[/tex], [tex]\( 1 \)[/tex], and [tex]\( 6i \)[/tex], we need to determine another root of the function.

### Step-by-Step Solution:

1. List the Given Roots:
- The roots given are [tex]\( -8 \)[/tex], [tex]\( 1 \)[/tex], and [tex]\( 6i \)[/tex].

2. Understanding Polynomial Roots:
- For polynomials with real coefficients, if a complex number is a root, its complex conjugate must also be a root.
- A complex number and its conjugate have the same real part and opposite imaginary parts.
- Here, [tex]\( 6i \)[/tex] is a complex number.

3. Identify the Complex Conjugate:
- The complex conjugate of [tex]\( 6i \)[/tex] is [tex]\( -6i \)[/tex].

4. Verify the Options:
- [tex]\( -6 \)[/tex]: Not a conjugate of [tex]\( 6i \)[/tex]; this is a real number.
- [tex]\( -6i \)[/tex]: This is the conjugate of [tex]\( 6i \)[/tex].
- [tex]\( 6-i \)[/tex]: This has a complex part but is not the conjugate of [tex]\( 6i \)[/tex].
- [tex]\( 6 \)[/tex]: This is a real number but not the conjugate.

5. Conclusion:
- Since [tex]\( -6i \)[/tex] is the conjugate of [tex]\( 6i \)[/tex], and for polynomials with real coefficients, complex roots occur in conjugate pairs. Therefore, [tex]\( -6i \)[/tex] must also be a root of [tex]\( f(x) \)[/tex].

Thus, the missing root for the polynomial function [tex]\( f(x) \)[/tex] must be [tex]\( -6i \)[/tex].