来自《耶鲁大学开放课程：金融市场 第2集 第2集》

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  The present value of this--suppose it pays--
  它的现值就是...假设它需要支付
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  let's say it pays c pounds each year,
  我们假设它每年支付c英镑
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  so it would be c times this.
  然后这里也乘以c
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  It would be c times (1+g)3 in the third year, etc.,
  在第三年它就是三倍的(1+g)的三次方
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  Then the present value is equal to c/(r-g)--
  现值就相当于c/(r-g)
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  that's the formula for the value of a growing console.
  这就是上涨债务价值的公式
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  g has to be less than r for this to make sense
  g必须小于r才行得通
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  because if g--if it's growing faster than the rate of interest,
  因为如果g比利率涨的还快
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  then this infinite series will not converge and
  那么这个无穷序列就不会收敛
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  the value would be infinite.
  价值就是无穷了
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  You might ask, "Well then how does that make sense?"
  你们也许会问 那怎么行得通呢
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  What if the British government
  如果英国政府承诺