回复：回复：回复：Another method

You wrote

S(x) has a characteristc, which is
S(x) is a non-increasing fuction in (-1,0) and
S(x) is a non-decreasing fuction in (-infinity,-1),
S(-1) is the maximum, and S(-1)=1/4 is the solution

Without showing the S(x), it is hard to prove these claims, isn't it?