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

[ 1/1Inequality]
    Assignment:Find the solution set of inequality (1/n)*cos(nπ/2) <0.001 .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 1 inequality：
         ( 1 / n ) * cos ( n * π / 2 ) <0.001         (1)
        From the definition field of divisor
        x ≠ 0        (2 )

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    From inequality(1)：
         -9.005733 < n < -√85640923/√1750000 或  -5.003185 < n < -2.998091 或  -1.000637 < n < 0 或  0.999364 < n < 3.001911 或  4.996819 < n < 7.004459
    From inequality(2)：
         n < 0 或  n ＞ 0

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    From inequalities (1) and (2)
         -9.005733 < n < -√85640923/√1750000 或  -5.003185 < n < -2.998091 或  -1.000637 < n < 0 或  0.999364 < n < 3.001911 或  4.996819 < n < 7.004459     (3)

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    The final solution set is :
         -9.005733 < n < -√85640923/√1750000 或  -5.003185 < n < -2.998091 或  -1.000637 < n < 0 或  0.999364 < n < 3.001911 或  4.996819 < n < 7.004459

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