x^3+x+2 = (x^3+1) + (x+1) = (x+1)(x^2-x+1) + (x+1)
I'll let you do the rest
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Alternatively, the easier method:
We do the 'sub in values', method, where you sub in values that are factors of 2, so sub in, x=-1, x=1, x=2, x=-2, see which one gives a solution.
We find that x=-1 is...