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

[ 1/1Inequality]
    Assignment:Find the solution set of inequality (-2000+500/(1+r)+700/(1+r)^2+2000/(1+r)^3) >(-10000+8000/(1+r)+2500/(1+r)^2+2000/(1+r)^3) .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 1 inequality：
         ( -2000 + 500 / ( 1 + r ) + 700 / ( 1 + r ) ^ 2 + 2000 / ( 1 + r ) ^ 3 ) > ( -10000 + 8000 / ( 1 + r ) + 2500 / ( 1 + r ) ^ 2 + 2000 / ( 1 + r ) ^ 3 )         (1)
        From the definition field of divisor
         1 + x ≠ 0        (2 )
        From the definition field of divisor
         1 + x ≠ 0        (3 )
        From the definition field of divisor
         1 + x ≠ 0        (4 )
        From the definition field of divisor
         1 + x ≠ 0        (5 )
        From the definition field of divisor
         1 + x ≠ 0        (6 )
        From the definition field of divisor
         1 + x ≠ 0        (7 )

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    From inequality(1)：
         r < -1.198128 或  r ＞ 0.135628
    From inequality(2)：
         r < -1 或  r ＞ -1
    From inequality(3)：
         r < -1 或  r ＞ -1
    From inequality(4)：
         r < -1 或  r ＞ -1
    From inequality(5)：
         r < -1 或  r ＞ -1
    From inequality(6)：
         r < -1 或  r ＞ -1
    From inequality(7)：
         r < -1 或  r ＞ -1

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    From inequalities (1) and (2)
         r < -1.198128 或  r ＞ 0.135628    (8)
    From inequalities (3) and (8)
         r < -1.198128 或  r ＞ 0.135628    (9)
    From inequalities (4) and (9)
         r < -1.198128 或  r ＞ 0.135628    (10)
    From inequalities (5) and (10)
         r < -1.198128 或  r ＞ 0.135628    (11)
    From inequalities (6) and (11)
         r < -1.198128 或  r ＞ 0.135628    (12)
    From inequalities (7) and (12)
         r < -1.198128 或  r ＞ 0.135628    (13)

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    The final solution set is :
         r < -1.198128 或  r ＞ 0.135628

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