.-. you guys (and gals) are too fast at this stuff

To be fair, 17 hours is a bit of a wait...

Yeah true

That depends: I can cast delete votes only if the question is well seasoned (two days closed or on hold).

@ProfessorVector We also have to wait, unless its score is −3 or something like that.

Asker admits this is homework, and it's a PSQ... @user21820, @Did, @ProfessorVector, @XanderHenderson Close votes anyone? Same asker asked this homework PSQ.

PSQ from asker who has asked only PSQ's

Perhaps I'm missing something, but how did this question earn 3 upvotes?

@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'."

@ProfessorVector exactly!

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)

I certainly think that "no effort homework" is on topic, here. But I can't tell if it really has grown, lately, because I'm here for less than a year.