k_i肯定和第一个等号后的分母有关。这个分母是怎么定义的？what is the meaning of x_i and epsilon_i. Not everyone has the book you mentioned. In the mean time, not everyone having the book wants to answer your question. You've got to post more information.

复习的时候这一段直接跳过，我完全看不懂。。。

那个ki是每一项前的系数~~~~

顶上。。。。

我当时也是琢磨了好久，也没推出来。。。倒是把ki那个求和的式子用等比求和就能得到1/Φ(B)。