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Math Help - Rational limit involving e?

  1. #1
    Member nautica17's Avatar
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    Rational limit involving e?

    Need some help with this one:

    lim x-> inf of (1-e^x) / (1+e^x)

    The answer should be -1 but I don't get how that is so. When you plug in infinity you get -inf/inf right? How does this problem work out algebraically?
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  2. #2
    Math Engineering Student
    Krizalid's Avatar
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    \frac{1-e^{x}}{1+e^{x}}=\frac{e^{-x}-1}{e^{-x}+1}, can you compute its limit now?
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  3. #3
    Member nautica17's Avatar
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    Quote Originally Posted by Krizalid View Post
    \frac{1-e^{x}}{1+e^{x}}=\frac{e^{-x}-1}{e^{-x}+1}, can you compute its limit now?
    Thank-you! I get it now!
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