Best Approximations: Solving (e^x,p_1)

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SUMMARY

The discussion centers on the approximation of the integral (e^x, p_1) defined as ∫^1_0 e^x(x - 1/2)dx. The user attempts to solve this integral and arrives at a result of (e^x, p_1) = (2.7/2) - (1/2), expressing confusion regarding the expected result of (1/2)(3 - e). The conversation emphasizes the importance of verifying the anti-derivative and the arithmetic involved in the evaluation process, suggesting that the user should ensure the problem setup is correct and compare results with the answer key.

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Homework Statement



The following is a worked example:

[PLAIN]http://img18.imageshack.us/img18/122/57926907.gif
[PLAIN]http://img717.imageshack.us/img717/8884/82726904.gif

I don't understand why they have got (e^x,p_1) equal to \frac{1}{2}(3-e)! :confused:

The Attempt at a Solution



(e^x,p_1)=\int^1_0 e^x(x-\frac{1}{2})dx

=\left[ xe^x-e^x- \frac{e^x}{2}\right]^1_0

=\frac{2.7}{2}-\frac{1}{2}

I don't get (e^x,p_1)=\frac{1}{2}(3-e).

Is there something wrong with what I'm doing?
 
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Where'd that 2.7 come from?

Anyways, you seem to have done two things:
  • Antidifferentiated
  • Plugged in numbers
Can you think of a way to check if your anti-derivative is correct?
Can you think of a way to check if you plugged in numbers and did arithmetic correctly?

It's probably worth checking that you set the problem up correctly too.

It's also worth checking that what you got and what the answer book got really are different. Can you think of a way to do that?
 

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