Integral with only one limit of integration?

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The discussion centers on the interpretation of an integral with a single limit of integration, specifically \int^x \frac{x'dx'}{1+x'^2}. Participants clarify that this notation represents an indefinite integral rather than a definite one. It is emphasized that the variable inside the integral is a dummy variable, and the upper limit indicates the variable to use in the resulting function. There is a caution against assuming a lower limit of 0, as this is not justified in this context. The key takeaway is to treat it as an indefinite integral and avoid imposing limits without proper justification.
DieCommie
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Homework Statement


Work it out with pencil and paper.
\int^x \frac{x'dx'}{1+x'^2}


Homework Equations


none


The Attempt at a Solution


My only question is what does it mean to have only one limit of integration? I am used to doing integrals in the indefinite case with no limits of integration, or in the definite case with two limits of integration.

What does this single limit of integration mean, and what do I do with it? Do I assume 0 for the other limit? Do I just solve it as a an indefinite integral?

Thanks for any clues!


 
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I've never seen that notation before! I'd say you just integrate it indefinitely, then substitute x in for x'.
 
Yeah, I'd say set the bottom limit equal to 0 so that it makes the second part of the solution disappear.
 
The notation \int^x f(x')dx' is just an indefinite integral. Remember that the variable inside the integral is a "dummy" variable- the "x" as a limit of integration just tells you what variable to use in the resulting function.

Do NOT set the bottom limit to 0! That is not justified.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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