Integration by parts Theory Problem?

In summary, the second degree polynomial P(x) that has the following properties is: (a) P(0)=1, (b) P'(0)=0, (c) the indefinite integral ∫P(x)dx/(x^3(x-1)^2) has no logs in the final answer.
  • #1
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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  • #2
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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  • #3
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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  • #4
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.
 

Related to Integration by parts Theory Problem?

What is integration by parts theory?

Integration by parts theory is a mathematical technique used to evaluate integrals that are products of two functions. It is based on the product rule of differentiation and allows us to solve integrals that would otherwise be difficult or impossible to solve.

What are the steps involved in integration by parts?

The steps involved in integration by parts are:

  • Identify the two functions in the integral that can be written as a product.
  • Choose which function will be differentiated and which will be integrated.
  • Apply the product rule to find the derivative of one function and the antiderivative of the other.
  • Plug in the values into the integration by parts formula: ∫u dv = uv - ∫v du
  • Simplify and solve for the integral.

When should integration by parts be used?

Integration by parts should be used when the integral is a product of two functions, and other methods such as substitution or trigonometric identities are not applicable.

What are the common mistakes made in integration by parts?

Some common mistakes made in integration by parts include:

  • Choosing the wrong functions to differentiate and integrate.
  • Forgetting to include a constant of integration when finding the antiderivative.
  • Incorrectly applying the product rule to find the derivative.
  • Not simplifying the resulting integral after applying the integration by parts formula.

What are some tips for solving integration by parts problems?

Some tips for solving integration by parts problems include:

  • Choose the function to differentiate based on the pattern LIATE (Logarithmic, Inverse trigonometric, Algebraic, Trigonometric, Exponential).
  • When in doubt, try differentiating both functions and choosing the one that simplifies the original integral the most.
  • Pay attention to the signs when applying the integration by parts formula.
  • If the integral becomes more complicated after applying integration by parts, you may need to repeat the process.

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