从衡量risk aversion的公式（A-P定义）的定义入手，书中一般有常风险偏好对应的效用方程的形式。

By the definition of relative rsik aversion，cu"(c)/u'(c)=-k(k constant),

   integrate cu"(c)=-ku'(c): cu'(c)-u(c)=-ku(c)

   u'(c)/u(c)=(1-k)/c

   integrate again: ln u(c)=(1+k)lnc
  
   u(c)=dc^(1+k)
   Next, by cu"(c)/u'(c)=k, you can get d=1/1-k.

Similarly, you could solve the cae for risk aversion.

Sorry, one typo: 1+k change to 1-k in  some formulas.