I was going to stay out of this, as I loosely agree with The Chaz and Andre. But as there is another answer that I am completely and totally against, I will enter the fray.
Let me be precise: In Michael Greinecker's answer there is the line:
But I agree, banning might be preferable to downvoting in this case.
And the comment by user1729:
Certainly, if his being here is contributing to his failing test [sic] then he should be banned. It is in his own interest!
Whether or not the POP (Person of the Original Post) "shows any research effort, is unclear or not useful" (taken from the hover-over downvote description) should in no way lead to any talk or action towards banning/suspending him. It is fortunate that suspension, deletion, and destruction are mod-controlled.
FWIW, I don't downvote POP's questions, and nor do I give explicit answers. I understand a certain desire to do so, as POP has a tendency to not show any research effort and apparently to spurn resources such as his professor, his textbook, and sites such as Paul's Online Math Notes.
Although I think that the lack of 'any research effort' is a sufficient reason to downvote in general, I am very torn as to whether or not it would serve any purpose in this case. The only thing missing from POP's questions are his own work. If it were the case that downvoting would force POP to post his own work, or at least his attempts, before getting answers, then that would be great. But this seems unlikely, for a lack of consensus and similar reasons preventing a consolidated homework policy.
To end, I wanted to note that it is not as if he is completely unwilling to put in work. On multiple occasions, I have gone into an extended chat discussion with him on his problems, where he arrived at the answer.
downvote maybe, preferably not; explicitly answer maybe, preferably not; but ban/suspend absolutely not.