Find an annihilator of x^2 + 2x^5

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Homework Help Overview

The discussion revolves around finding an annihilator for the expression x² + 2x⁵, which falls under the subject area of differential operators in the context of linear algebra or differential equations.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the concept of annihilators and discuss the implications of using different operators, such as D³ and D⁶. Questions arise about the existence of multiple annihilators and whether the least common multiple should be chosen. There is also inquiry into the meaning of certain equations and the rationale behind multiplying annihilators.

Discussion Status

The discussion is active, with participants questioning assumptions about annihilators and exploring the relationships between different operators. Some guidance has been provided regarding the nature of annihilators, but no consensus has been reached on the best approach to take.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is also a focus on understanding the definitions and implications of the operators involved.

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Homework Statement


Find an annihilator of x2+2x5.

Homework Equations


xnecx -----> [D-c]n+1

[Q1(D)Q2(D)] = b1(x) + b2(x)

The Attempt at a Solution


[/B]
x2 -----> D3

2x5-----> D6

x2 + 2x5 ------> (D3)(D6) = D18

The answer should be D6.
 
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magnesium12 said:

Homework Statement


Find an annihilator of x2+2x5.

Homework Equations


xnecx -----> [D-c]n+1

[Q1(D)Q2(D)] = b1(x) + b2(x)

The Attempt at a Solution


[/B]
x2 -----> D3

2x5-----> D6

x2 + 2x5 ------> (D3)(D6) = D18

The answer should be D6.
Doesn't the D6 operator also annihilate x2?
 
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Mark44 said:
Doesn't the D6 operator also annihilate x2?

I guess it does. So does that mean there can be multiple annihilators and they'll all work? Or should you always pick the least common multiple?
 
magnesium12 said:

Homework Statement


Find an annihilator of x2+2x5.

Homework Equations


xnecx -----> [D-c]n+1

[Q1(D)Q2(D)] = b1(x) + b2(x)
What does the last line mean? It's not clear to me.

The Attempt at a Solution


[/B]
x2 -----> D3

2x5-----> D6

x2 + 2x5 ------> (D3)(D6) = D18

The answer should be D6.
Why are you multiplying the two annihilators?
 
magnesium12 said:
(D3)(D6) = D18
Didn't notice this before -- is x3x6 = x18?
 
magnesium12 said:
I guess it does. So does that mean there can be multiple annihilators and they'll all work? Or should you always pick the least common multiple?
Dn+1 annihilates xn and all lower powers of x. I don't see that this is related to the LCM in any way.
 
Mark44 said:
Didn't notice this before -- is x3x6 = x18?
Heh...I didn't notice that either.
 

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