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

[ 1/1Inequality]
    Assignment:Find the solution set of inequality 64 <= 420+6/a <= 100 .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 2 inequalities：
        64 <= 420 + 6 / a         (1)
         420 + 6 / a <= 100         (2)
        From the definition field of divisor
        x ≠ 0        (3 )

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    From inequality(1)：
         a ∈ R (R is all real numbers),that is, in the real number range, the inequality is always established!
    From inequality(2)：
        The solution set is empty, that is, within the range of real numbers, the inequality will never be established!
    From inequality(3)：
         a < 0 或  a ＞ 0

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    The final solution set is :
        The solution set is empty,that is, the inequality will never be estatlished within the real number range.

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