Proving Normality of Homomorphic Image and Subgroup - Abstract Algebra Homework

[lorena82186]

Homework Statement

If f is a homomorphism of G onto G' and N is a normal subgroup of G, show that f(N) is a normal subgroup of G'.

Homework Equations

The Attempt at a Solution

Once again, I'm completely lost.

 

[Dick]

Under a homomorphism, h(ab)=h(a)h(b). Put this together with the definition of a normal subgroup and remember h is 'onto'. This is not that hard. You just need to get started.