Find a polynomial f(x) in Z[x] such that r is a root and use f(x) to show that r is irrational.

r=sqrt(3-sqrt(5))

The hint says r^2=3-sqrt(5), so (r^2-3)^2=?

So I suppose they don't just want (x-sqrt(3-sqrt(5)), but I don't know how to construct a polynomial so that I can show the irrationality.

Thanks.