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For which primes $p$ is there a root to the equation $x^3+x^2-2x-1$ mod $p$? I have no idea where to start, any help is appreciated! Thank you

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    A place to start is just trying some primes (by hand, or with a computer) and looking for patterns. Usually this technique doesn't work very well, but it is better than doing nothing.2012-08-05
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    I think you need to compute the discriminant of the polynomial in $\mathbb{Q}$.2012-08-05

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