If you had a perpetuity, which paid C/2 forever, you already know from the perpetuity formula that the value of that would be C/2 divided by r/2 if r/2 is the discount rate.

如果你有一只永续债券,每半年付息C/2,没有到期日,从永续债券的公式可以知道,债券价格等于C/2除以r/2,r/2为贴现率

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