Evaluate the integral(x^e + e^x) from (-1 to 1)
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Evaluate the integral(x^e + e^x) from (-1 to 1)

[From: ] [author: ] [Date: 12-04-14] [Hit: ]
Upon further review, it seems -1 is out of the domain of f(x) = x^e + e^x. So..........
I'm getting hung up when I take the antiderivative of x^e, I get x^(e+1)/(e+1). But when I plug -1 into this my calculator gets an error. Upon further review, it seems -1 is out of the domain of f(x) = x^e + e^x. So....when integrating, do I only go from 0 to 1 since anything less than 0 does not exist?

NOTE: I'm interested in explanations only, not just answers, and not links to wolfamalpha.com.

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I think you'd have to say this integral doesn't exist. Think about how the integral is defined in terms of a Riemann sum which requires f(x1), f(x2), ... f(xn) at intervals from -1 to 1. Some of those values don't exist, so the Riemann sum doesn't exist, so the limit of the sum which is the integral doesn't exist.

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I'm not going to link to it, because you told me not to. But Wolfram gives me an answer of

e - 1/e + ( 1 + cos(eπ) + sin(eπ)√-1 )/(1+e)

or about

2.44904+0.208145√-1

The cheeky answer is that your calculator isn't expensive enough to do this integral. The serious answer is that you've stumbled upon a very deep question in mathematics that is omitted from the standard curriculum, because of prejudice against a beautiful number that was slandered four centuries ago by the word 'imaginary'.

Of course, the *practical* answer is that if -1 isn't in the domain of x^e, then you shouldn't try to do any surgery without your teachers permission. Just write "the integral from -1 to 1 is not defined, and here's why. However, the integral from 0 to 1 is well-defined and its value is ____."
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