Find a degree 4 polynomial with real coefficients which has complex roots 2-i and 1+2i

Complex roots of polynomials with real coefficients occur in conjugate pairs so

y = a(x - 2 + i)(x - 2 - i)(x - 1 + 2i)(x - 1 - 2i) =
a(x^2 - 4x + 5)(x^2 - 2x + 5) =
a(x^4 - 6x^3 + 18x^2 - 3x + 25)
where a is any real number is the required set of polynomials.