In some cases, a square root of a negative number must exist in order to determine the roots of a cubic equation. An educational presentation provides a specific example of a cubic with a known root to have an understanding of a square root of a negative number.

Concepts

imaginary numbers, complex numbers, cubic functions

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Additional Tags

math

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Instructional Ideas

• Have the class use del Ferro's formula presented in the video to confirm roots of cubic functions
• Research Cardan's formula for cubic equations that include the x squared term and confirm that it works for cubics with real roots

Classroom Considerations

• Second video in a nine-part series

• This video is hosted on YouTube

Pros

• Provides a historical view of why being able to take a square root of a negative number was necessary
• Continues the progression of the history of complex numbers from the first video

Cons

• None

Common Core

HSN-CN.A.1 MP2 MP7