Asker admits this is homework, and it's a PSQ... @user21820, @Did, @ProfessorVector, @XanderHenderson Close votes anyone? Same asker asked this homework PSQ.
@amWhy Good question. Especially since "I understand the idea but am having some trouble writing the formal proof." is merely the translation of "I can't be bothered to look up the definition of 'subspace' or 'linear space'."
I'm honestly dismayed with the amount of no effort homework questions lately. Has it always been like that and I just haven't noticed before? (If this chat allows for this kind of general talk)