There exists a polynomial of the form
x^6 + ax + b
that has the same set of real roots as the polynomial
x^2 - 2x - 1
This can be solved quickly starting with a single polynomial division:
(x^6)/(x^2-2x-1) = x^4+2x^3+5x^2+12x+29 + (70x+29)/(x^2-2x-1)
For x^6+ax+b to be a polynomial multiple of x^2-2x-1, ax+b must be the negative of the remainder of the division:
ax+b = -(70x+29) = -70x-29. Then |-70 + -29| = 99.