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Algebra 2
41. CC.HSN.CN.A.1
41.2 Introduction to imaginary numbers
Introduction to Imaginary Numbers
Find out what the imaginary unit i really means, why negative numbers can have square roots, and how powers of i repeat in a cycle.
What You'll Learn
Define the imaginary unit i as the number whose square equals negative one.
Simplify square roots of negative numbers by rewriting them using i.
Recognize that no real number squared can ever produce a negative result.
Apply the repeating four-step cycle of powers of i to simplify any power quickly.
Connect imaginary numbers to complex numbers as the building block for the complex plane.
What You'll Practice
1
Simplifying roots of negative numbers like (-16) and (-40)
2
Evaluating powers of i from i³ to i²
3
Simplifying complex expressions with fractional exponents involving negative bases
4
Converting imaginary number expressions into simplified real or imaginary results
Why This Matters
Imaginary numbers are essential for solving equations that have no real solutions, like x² = -1. You'll use them throughout advanced algebra, precalculus, calculus, engineering, and physics to work with complex numbers, electrical circuits, and wave functions.
Before You Start — Make Sure You Can:
This Unit Includes
2 Video lessons
Practice exercises
Learning resources
Skills
Imaginary Numbers
Complex Numbers
Radicals
Exponents
Simplification
Powers of i

IL Curriculum Aligned