Integration by parts Theory Problem?

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Homework Help Overview

The problem involves finding a second degree polynomial P(x) that satisfies specific conditions related to its value, derivative, and an indefinite integral. The context is within the subject area of integration, specifically focusing on integration techniques and polynomial functions.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the formulation of the polynomial based on given conditions and explore the integration of the polynomial with a rational function. There are attempts to apply integration by parts, but concerns arise regarding the appearance of logarithmic terms in the solution.

Discussion Status

Some participants have provided hints regarding the value of the constant 'a' and suggested that the problem may be more aligned with partial fractions rather than integration by parts. There is acknowledgment of a shift in understanding as participants reconsider the integration method being applied.

Contextual Notes

Participants note the requirement that the solution cannot include logarithmic terms, which influences the choice of the constant 'a'. There is also mention of the problem's placement in the integration by parts section of a textbook, which may have led to initial confusion.

MidgetDwarf
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Find the second degree polynomial P(x) that has the following properties: (a) P(0)=1, (b) P'(0)=0, (c) the indefinite integral ∫P(x)dx/(x^3(x-1)^2). Note: the the indefinite integral is a rational function. Cannot have Log terms occurring in solution.

first. I use the generic polynomial aX^2+bx+c.

When P(0)=1=C. Therefore C=1. Taking the derivative of the generic polynomial, P'(X)=2aX+B.
When P'(0)=0=B. Therefore B=0.

So far for the generic polynomial I have. P(X)= aX^2+1.

for the integral:∫(aX^2+1)dx/(X^3(x-2)^2)

breaking up the integral. ∫(aX^2)dx/(x^3(x-1)^2)+∫dx/(x^3(x-1)^2

=a∫dx/x(x-1)^2+∫dx/(x^3(x-1)^2).

The problem is. No matter how I did the the integration by parts, either choice for u. I get a ln terms for solution.

Is there something I missing?
 
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Yes you are missing something. You are missing the value of the constant a. That's a hint. What value of the constant a will satisfy the requirement that there are no logs in the final answer?
 
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This not a problem in "integration by parts", it is a problem in integration by "partial fractions". Perhaps you just miswrote that. What do you get if you rewrite the integrands in terms of "partial fractions"?
 
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HallsofIvy said:
This not a problem in "integration by parts", it is a problem in integration by "partial fractions". Perhaps you just miswrote that. What do you get if you rewrite the integrands in terms of "partial fractions"?
I thought it was an integration by parts question because it appears in the integration by parts section of my book.

Upon reading your post and the previous poster, and using the method of partial fractions it became very clear. it is a=-3. If a=-3, then the ln terms "cancel", which makes all 3 conditions true.

A very fun problem.

thanks a lot.
 

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