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Math Help - Sign Chart - Critical Value Method

  1. #1
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    Post Sign Chart - Critical Value Method

    Dear Forum I am trying to figure out the following , but I am having no luck, please help if possible

    Solve x^2 + 11x + 18 > 0 using the Critical Value (Sign Chart) method.



    Thanks -AC-
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  2. #2
    Senior Member mollymcf2009's Avatar
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    Quote Originally Posted by AlgebraicallyChallenged View Post
    Dear Forum I am trying to figure out the following , but I am having no luck, please help if possible

    Solve x^2 + 11x + 18 > 0 using the Critical Value (Sign Chart) method.



    Thanks -AC-
    First, factor your inequality to get:

    (x+9)(x+2) > 0

    -9 & -2 are your critical values, so put those on your sign chart.
    Then to the right of the chart, write your two factors. Choose values in the intervals between each and write the sign for each.
    You should have:
    - two negatives for the interval from (-\infty, -9) => +

    - a positive and a negative for the interval from (-9,-2) => -

    - two positives for the interval from (-2,\infty) => +

    So, the question is asking you:
    Where is x^2 + 11x +18 GREATER than zero?

    So your answer is: (-\infty,-9) U (-2,\infty)
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