Let

be a cubic polynomial with integer coefficients with leading coefficient

and with one of its roots equal to the product of the other two. Show that

is a multiple of
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Let $p(x)$ be a cubic polynomial with integer coefficients with leading coefficient $1$ and with one of its roots equal to the product of the other two. Show that $2p(-1)$ is a multiple of $p(1)+p(-1)-2(1+p(0)).$