Suppose I have the following integral:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]\int_{2}^{∞} \frac{1}{x^2-x}dx [/tex]

Before substituting the boundaries I get

ln|x-1| - ln|x|.

When I put the boundaries in I get

∞ - ∞ - 0 + ln(2) = ln(2). But how do I know those infinities cancel?

Is it because both are infinities of real numbers and therefore are the same size? Is there some other reason?

Thank for any insight.

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# I How do you know when ∞ - ∞ is zero?

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