This is a wonderful method.

來源: 2010-09-13 15:42:19 [博客] [舊帖] [給我悄悄話] 本文已被閱讀:

for x(a-x)(a+x)=[(1-c)x(a-x)(ca+cx)]/c(1-c), why do you introduce c(1-c). Is there any systematic patten to treat this kind of problem?