10
practice examMultiple Choice

Practice Exam

Question 10 • Mathematics II

One root of a third degree polynomial function f of x is negative 5 plus 2 i Which statement describes the number and nature of all roots for this function?

Answer
A
f of x has two real roots and one imaginary root.
B
f of x has three imaginary roots.
C
f of x has three real roots.
D
f of x has two imaginary roots and one real root.

Explanation

For a polynomial with real coefficients, any non-real complex root must come with its complex conjugate. Since −5 + 2i is a root, −5 − 2i is also a root. These are two non-real roots, and a third-degree polynomial has one root left, which must be real. Thus, the function has two imaginary roots and one real root.

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