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ax^2 + bx + c = a(x - x_2)(x - x_3), 3x3 system

Source: Polish MO Second Round 1972 p1

September 8, 2024
algebrasystem of equationsSystem

Problem Statement

Prove that there are no real numbers a,b,c a, b, c , x1,x2,x3 x_1, x_2, x_3 such that for every real number x x ax2+bx+c=a(xx2)(xx3) ax^2 + bx + c = a(x - x_2)(x - x_3) bx2+cx+a=b(xx3)(xx1)bx^2 + cx + a = b(x - x_3) (x - x_1) cx2+ax+b=c(xx1)(xx2)cx^2 + ax + b = c(x - x_1) (x - x_2) and x1x2 x_1 \neq x_2 , x2x3 x_2 \neq x_3 , x3x1 x_3 \neq x_1 , abc0 abc \neq 0 .