Understanding Non-Real Eigenvalues to Solving Homework Problems

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In summary, the general form for the given equations is x1(t)=-C1sin(3t)*a + C1cos(3t)*b and x2(t)=C2sin(3t)*a + C2cos(3t)*b, where v=a+ib and the constants C1 and C2 are not necessarily the same in both functions. The given problem involves finding the values of a and b, which are determined by the given vector v.
  • #1
cowmoo32
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Homework Statement


et0re.jpg




The Attempt at a Solution


I know the general form should be

x1(t)=-C1sin(3t) + C2cos(3t)
x2(t)=C1sin(3t) + C2cos(3t)

but there's something going on with v that I'm not getting. I'm not sure how to incorporate it without knowing A
 
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  • #2
cowmoo32 said:

Homework Statement


et0re.jpg




The Attempt at a Solution


I know the general form should be

x1(t)=-C1sin(3t) + C2cos(3t)
x2(t)=C1sin(3t) + C2cos(3t)
The constants shouldn't be the same in both functions.
cowmoo32 said:
but there's something going on with v that I'm not getting. I'm not sure how to incorporate it without knowing A
 
  • #3
Whoops, I wrote that wrong. All of the problems I have worked so far have had the form:x1(t)=-C1sin(3t) + C1cos(3t)
x2(t)=C2sin(3t) + C2cos(3t)
 
  • #4
After looking through some more examples, the answer will have the form


x1(t)=-C1sin(3t)*a + C1cos(3t)*b
x2(t)=C2sin(3t)*a + C2cos(3t)*b

where v=a+ib

v = [-1-i,1] = [-1,1]+i[-1,0]

a=[-1,1]
b=[-1,0]

I get:
C1sin(3t)
-C2cos(3t)

But it's telling me that's incorrect.
 

FAQ: Understanding Non-Real Eigenvalues to Solving Homework Problems

What are non-real eigenvalues?

Non-real eigenvalues are complex numbers that cannot be represented on the real number line. They are typically denoted by the letter "i" and have the form a + bi, where a and b are real numbers and i is the imaginary unit.

Why do we need to understand non-real eigenvalues?

Non-real eigenvalues are important in solving mathematical and engineering problems that involve complex systems. They can help us understand the behavior and stability of these systems, and finding their corresponding eigenvectors can provide valuable insights into the underlying dynamics.

How do we solve homework problems involving non-real eigenvalues?

To solve problems involving non-real eigenvalues, we typically use the same methods as we would for real eigenvalues. This includes finding the characteristic equation, determining the eigenvalues, and finding the corresponding eigenvectors. However, we must also be familiar with complex numbers and their operations, such as conjugation and multiplication by the imaginary unit.

What are some common mistakes when dealing with non-real eigenvalues?

One common mistake is forgetting to include the imaginary unit when writing the complex eigenvalues. Another mistake is incorrectly calculating the eigenvectors by not taking into account the complex numbers. It is also important to remember that the eigenvectors for non-real eigenvalues will also be complex.

Can non-real eigenvalues have real eigenvectors?

No, non-real eigenvalues can only have complex eigenvectors. This is because the corresponding eigenvectors must satisfy the eigenvalue equation, which involves complex numbers. Real eigenvectors can only exist for real eigenvalues.

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