Find all integers n for which the equation x³ - 13x + n = 0 has three integer roots.

(In reply to Some thoughts by Federico Kereki)

"pq-p(p+q)-q(p+q)=-13, so p²+pq+q²=-13" has the wrong sign on the 2nd equation, and the following equations then also have the wrong sign. With the right sign, they all work with p=1, q=3 or with p=-1, q=-3.

Posted by Richard on 2006-10-14 22:04:37