Problem preview
N-CN.9 Warmup M3-046-A03-V01

Know the Fundamental Theorem of Algebra and connect it to polynomial roots.

Find missing polynomial roots from the degree, counting multiplicity

Problem

A real-coefficient cubic has roots \(2\) and \(1~+~i\). Find the remaining root.

Big Picture

What this problem is really about

A polynomial with real coefficients cannot have an unpaired nonreal root. Complex conjugation keeps the real part and reverses only the imaginary sign, producing the companion root required by the conjugate-root theorem. After supplying that partner, count all known roots with multiplicity to confirm that they fill the polynomial's degree.

Inside Gozunta

Turn the preview into practice.

More than a preview

Gozunta lets you study this problem—and more than 10,000 others.

Create targeted learning sessions, use hints, check your answer, read the walkthrough, watch the video, print the work, and track your progress.

Discover Gozunta Try it now
Four variants of this problem type
Curriculum context
Course
Math III
Standard
N-CN.9
Category
Number and Quantity
Domain
The Complex Number System
Objective
Know the Fundamental Theorem of Algebra and connect it to polynomial roots.
Problem type
Find missing polynomial roots from the degree, counting multiplicity