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Quadratic equation with complex numbers in 3D

Hello! Since school, solving quadratic equations (KU), for example x2+x+1=0, got roots with an imaginary component, x= frac12 pmi frac sqrt32and if you want to see how the graph crosses the axis Yin points x= frac12 pmi frac sqrt32, I found on the Internet graphics like:


How does the graph with the imaginary part look (in my thoughts) in 3D ( X botY botI), and is the topic of this article.

PS: Under the cut heavy animations

As usual, the graph of f-ktsii consists of points, and points are under construction on intersection of axes Xand Y.
The schedule of f-tsii with a complex component Ycomplex=F(Xcomplex),
')
Where Xcomplex=Xre+Xim= beginbmatrixXreXim endbmatrix- vector


Ycomplex=Yre+Yim= beginbmatrixYreYim endbmatrix- vector


Xcomplexcan be represented as a 3-dimensional vector  beginbmatrixXre0Xim endbmatrix
[Xre]Xaxis
[0]Yaxis
[Xim]axisI
Similarly Ycomplex beginbmatrix0YreYim endbmatrix
[0]axisX
[Yre]Yaxis
[Yim]axisI

Intersection point Xcomplexand Ycomplexwill be equal to the sum of the vectors Xcomplexand Ycomplex

 beginbmatrixXre0Xim endbmatrix+  beginbmatrix0YreYim endbmatrix=  beginbmatrixXreYreXim+Yim endbmatrix

With the intersection figured out.

Next to build the graph you need to decide on the change Xreand Ximalong the axis Xcomplex, for this you need root KU. There are two options:

  1. To make Ximconstant and change only Xrefrom the root of KU;
  2. Get the angle between Xreand Ximfrom the root ku and move along Xcomplexbuilding up Xre, Ximcalculate taking into account the angle and Xre.

I chose the second option. Take for example:

x2+x+1=0

Roots ku

X1=0.5+0.866i
angle=300°
X2=0.50.866i
angle=60°

When angle=300°


When the angle is 0, the graph looks like it used to look like at school:


Changing the angle, we see how the graph changes:


PS: The presented graphics and their animations were created in the “Quadratic Complex 3D Graph” application from Google Apps.

Source: https://habr.com/ru/post/329672/


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