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Math Help - Limits with Infinity

  1. #1
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    Limits with Infinity

    Use a table of values of f(x) to estimate the value of the limit to four decimal places.

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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by zweevu View Post
    Use a table of values of f(x) to estimate the value of the limit to four decimal places.

    note that you have (by multiplying by the conjugate over itself):

    \lim_{x \to - \infty} (\sqrt{3x^2 + 9x + 5} - \sqrt{3x^2 + 3x + 2}) \cdot \frac {\sqrt{3x^2 + 9x + 5} + \sqrt{3x^2 + 3x + 2}}{\sqrt{3x^2 + 9x + 5} + \sqrt{3x^2 + 3x + 2}}

    Now what can you do?
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    Since it's to negative infinity, shouldn't there be a negative before the first radical?
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by zweevu View Post
    Since it's to negative infinity, shouldn't there be a negative before the first radical?
    no.

    what did you get after you simplified the expressions? Hint: you want to factor an x^2 out from underneath the square roots in the denominator, and you know what \sqrt{x^2} is, i suppose...
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