If p, q, r are the roots of $x^3-6x^2+3x+1=0$ determine the possible values of $p^2q+q^2r+pr^2$.

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If p, q, r are the roots of $x^3-6x^2+3x+1=0$ determine the possible values of $p^2q+q^2r+pr^2$. I tried to solve this problem through Vieta's relations but I did not find a way that allows not to use the cubic formula. I found this question on Pathfinder of Olympiad Mathematics and I have been struggling for a week without getting anywhere.

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Hint: Let \begin{eqnarray*} A=p^2q+q^2r+r^2p \\ B=pq^2+qr^2+rp^2. \end{eqnarray*} Now calculate $A+B$ and $AB$ ... and solve the quadratic.