MathDB
Coefficients of a polynomial

Source: Greece National MO 2015

March 4, 2015
algebrapolynomial

Problem Statement

Let P(x)=ax3+(ba)x2(c+b)x+cP(x)=ax^3+(b-a)x^2-(c+b)x+c and Q(x)=x4+(b1)x3+(ab)x2(c+a)x+cQ(x)=x^4+(b-1)x^3+(a-b)x^2-(c+a)x+c be polynomials of xx with a,b,ca,b,c non-zero real numbers and b>0b>0.If P(x)P(x) has three distinct real roots x0,x1,x2x_0,x_1,x_2 which are also roots of Q(x)Q(x) then: A)Prove that abc>28abc>28, B)If a,b,ca,b,c are non-zero integers with b>0b>0,find all their possible values.