February 17–February 23, 2009

Problem

Let f(x) = x4 + a x3 + b x2 + c x - c. Suppose that f shares two distinct integral roots with its derivative f'(x), and suppose that a,b, and c are not zero. Determine a, b, and c.

Solution

here

List of solvers

Wen Wang (undergrad); Justin Shih, Dustin Moody, Koopa Koo, Peizhe Shi (graduate); Gary M. Raymond (staff); David Kaplan, Lloyd Sakazaki, Chang Hai Bin, Adam Welly, Luan Nguyen (outside).

Chang Hai Bin wins the prize!