16.-Linear-Algebra-by-Kenneth-Hoffman · Problem 6.7.1
Elementary Canonical Forms
Mathematics — Linear Algebra · invariant-range-projection
Problem
Let E be a projection of V and let T be a linear operator on V. Prove that the range of E is invariant under T if and only if ETE=TE. Prove that both the range and null space of E are invariant under T if and only if ET=TE.