
Douglas B. answered 10/06/21
Algebra tutor with masters degree in applied math
One trick that's useful to know is that for polynomials with real coefficients, any complex roots come in pairs. So, if -isqrt(6) is a root, so is +isqrt(6).
So, one such polynomial would be:
(x+3)*(x-2)*(x+isqrt(6))*(x-isqrt(6))
=(x+3)*(x-2)*(x^2+6)
=(x+3)*(x^3-2x^2+6x-12)
=x^4+x^3+6x-36.