Yes, I realized that.

来源: 于 2015-10-16 17:01:49 [旧帖] [给我悄悄话] 本文已被阅读：次

The second part to find the f(x) is wrong because c is not 0. ( In solution we find that c must be 0 if d is not 0. But this is a contradiction.)

My solution is still right.