Consider the ring homomorphism ϕ : Z[x] →R defined by ϕ(x) =
√5.
Let I = {f ∈Z[x]|ϕ(f) = 0}.
First prove that I is an ideal in Z[x]. Then find g ∈ Z[x] such
that I = (g). [You do not need to prove the last equality.]
Give an example of a ring homomorphism f:R -> S where M is a
maximal ideal of R but M^e is not a maximal ideal of S
note that I^e - is the extension notation f(I)S generated by
f(I) as the entension of R, a commutative ring