Question

How to prove using first isomorphism theorem?

Answer 1

g ∈ K} = K/N. Thus by the First Isomorphism Theorem, (G/N)/(K/N) ∼ = G/K. Proof. The proof ideas are the same as in the proof of the Third Isomorphism Theorem, by using theFirst Isomorphism Theorem on the homomorphism φ : A → NA/N defined by φ(a) = Na.