Overview: 1 questions will be solved this time.Among them
           ☆1 inequalities

[ 1/1Inequality]
    Assignment:Find the solution set of inequality (x*(x+1))/2 <= 2009 .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 1 inequality：
         ( x * ( x + 1 ) ) / 2 <= 2009         (1)

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    From inequality(1)：
         -63.889668 ≤ x ≤ 62.889668

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    The final solution set is :
         -63.889668 ≤ x ≤ 62.889668

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