i have a try to convert this question to a geometric one

送交者: else 于 2016-05-29, 18:40:05:

f(x) is a parabola with a symmetric axis of x=(b+c)/2.
f(0)==p=bc/[(a-b)(c-a)] +
ac/[(b-c)(b-a)] +
ab/[(c-a)(c-b)]

thus this parabola is
f(x)=(x - (a-b)/2)^2 + p

eeh, should be f(x)=(x - (b+c)/2)^2 + p (无内容) - else (0 bytes) 2016-05-30, 03:36:49 (808991)