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Math Help - L'Hospital's rule not applicable?

  1. #1
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    L'Hospital's rule not applicable?

    Hi,

    I'm doing curve sketching and am trying to find vertical asymptotes for f(x) = 2 - 15x + 9x^2 -x^3

    I haven't studied L'H Rule for too long but I see that the lim as x approaches infinity would be 2 - infinity + infinity - infinity and wouldn't that be an indeterminate form? I can see that there are no asymptotes but any clarification on solving this type of limit is appreciated

    Looking at it again I'm guessing that the above solution is negative infinity since the function's highest power would go to negative infinity?
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  2. #2
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    Quote Originally Posted by DannyMath View Post
    Hi,

    I'm doing curve sketching and am trying to find vertical asymptotes for f(x) = 2 - 15x + 9x^2 -x^3

    I haven't studied L'H Rule for too long but I see that the lim as x approaches infinity would be 2 - infinity + infinity - infinity and wouldn't that be an indeterminate form? I can see that there are no asymptotes but any clarification on solving this type of limit is appreciated

    Looking at it again I'm guessing that the above solution is negative infinity since the function's highest power would go to negative infinity?
    You are sketching a cubic equation graph. I suggest you review your class notes, textbook, on-line resources etc. There are no asymptotes. l'Hopspital's is completely irrlevant here.
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