Homepage › Solution manuals › Sheldon Axler › Linear Algebra Done Right › Exercise 3.F.28
Proof. Similarly to Exercise 27, we have
v ∈ V : ψ(v) = 0 for every ψ ∈ null T′
=
v ∈ V : ψ(v) = 0 for every ψ ∈ span (φ)
v ∈ V : φ(v) = 0
v ∈ V : v ∈ null φ
= null φ
□