(In reply to Answer only (possible spoiler)
So annoying to get an integer answer without an explanation!
However, there is a similar problem, with x3 - x - 1 = 0, leading to a well-known sequence.
Now for x3 - x - 1 = 0, the roots are: x~~1.3247,x~~-0.66236-0.56228i, x~~-0.66236+0.56228i,
while for x3 - x + 1 = 0, the roots are:
x~~-1.3247, x~~0.66236-0.56228i, x~~0.66236+0.56228i, so there's just a sign change in the real part.
Since we are raising to an even power, the result is the same for either equation, see:
Posted by broll
on 2015-02-07 04:22:17