Eigenvector of complex Eigenvalues

In summary, the student attempted to solve for x_2 using two equations but got them incorrect. They were able to solve for x_2 using one equation after getting the first equation wrong.
  • #1
bowlbase
146
2

Homework Statement


##A=\begin{bmatrix} 16 &{-6}\\39 &{-14} \end{bmatrix}##



Homework Equations





The Attempt at a Solution



I did ##A=\begin{bmatrix} 16-\lambda &{-6}\\39 &{-14-\lambda} \end{bmatrix}##

and got that ##\lambda_1=1+3i## and ##\lambda_2=1-3i##

The solution is partially given for both the vectors:

##x_1=\begin{bmatrix} 1+i \\ ?+?i\end{bmatrix}##
I should fill in the "?". I tried placing 1+3i into replace lambda:

##\begin{bmatrix} 16-(1+3i) &{-6}\\39 &{-14-(1+3i) } \end{bmatrix}##
Which I then get:
##\begin{bmatrix} 15-3i &{-6}\\39 &{-15-3i } \end{bmatrix}##


I don't know what to do from here. I've tried all sorts of ways to get this figured out but I just keep getting the wrong answers.
 
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  • #2
bowlbase said:

Homework Statement


##A=\begin{bmatrix} 16 &{-6}\\39 &{-14} \end{bmatrix}##

Homework Equations


The Attempt at a Solution



I did ##A=\begin{bmatrix} 16-\lambda &{-6}\\39 &{-14-\lambda} \end{bmatrix}##

and got that ##\lambda_1=1+3i## and ##\lambda_2=1-3i##

The solution is partially given for both the vectors:

##x_1=\begin{bmatrix} 1+i \\ ?+?i\end{bmatrix}##
I should fill in the "?". I tried placing 1+3i into replace lambda:

##\begin{bmatrix} 16-(1+3i) &{-6}\\39 &{-14-(1+3i) } \end{bmatrix}##
Which I then get:
##\begin{bmatrix} 15-3i &{-6}\\39 &{-15-3i } \end{bmatrix}##I don't know what to do from here. I've tried all sorts of ways to get this figured out but I just keep getting the wrong answers.
Add -39 times the first row to 15 - 3i times the second row. That should result in the second row being all zeros. This seems to be a pretty messy problem to do by hand.
 
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  • #3
For whatever reason all of the problems for this section are like this. I just hope our test tomorrow is simpler...

Got ahead of myself on posting. 1 sec while I do what you said.

They did cancel so I'm left with

##(-585+117i)x_1=-234x_2##

##x_1=1+i=\frac{-234x_2}{-585+117i}##

which is ##x_2(\frac{135}{338}+\frac{27i}{338})=1+i##

so ##x_2=\frac{26}{9}+\frac{52i}{27}##

I got it wrong somewhere.
 
Last edited:
  • #4
I figure it out:

##(-585+117i)x_1+234x_2=0## where ##x_1=1+i##

##\frac{(-585+117i)(1+i)}{-234}=x_2##

##x_2=3+2i##

This is really exactly the same so I'm not sure what happened up there. Probably just calculations. I used my calculator once I had it in the second equation form.
 

Related to Eigenvector of complex Eigenvalues

What is an eigenvector of complex eigenvalues?

An eigenvector of complex eigenvalues is a vector that when multiplied by a complex matrix, results in a scalar multiple of itself. In other words, it is a vector that does not change direction when multiplied by a complex matrix.

How do complex eigenvalues differ from real eigenvalues?

Complex eigenvalues differ from real eigenvalues in that they can have both a real and imaginary component, while real eigenvalues are only composed of real numbers. Additionally, the eigenvectors corresponding to complex eigenvalues are also complex, while the eigenvectors corresponding to real eigenvalues are real.

What is the significance of complex eigenvalues in matrix operations?

Complex eigenvalues are significant in matrix operations because they allow for the representation of complex transformations. This is particularly useful in fields such as quantum mechanics and signal processing.

How are complex eigenvalues and eigenvectors calculated?

To calculate complex eigenvalues and eigenvectors, we first find the eigenvalues of the matrix using the characteristic equation. We then solve for the corresponding eigenvectors using the eigenvector equation. The resulting eigenvectors will be complex for complex eigenvalues.

What is the relationship between complex eigenvalues and the stability of a system?

The stability of a system is determined by the eigenvalues of its corresponding matrix. For systems with complex eigenvalues, the stability is determined by the real parts of the eigenvalues. If the real parts are negative, the system is stable, while if they are positive, the system is unstable. The imaginary parts of the complex eigenvalues do not affect stability.

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