"to not be..." "to be not..." "not to be..." Differences?

0 I am not bad a grammar, but I recently got asked a question I couldn't answer.02br
00What is the difference between the following sentences, and which sentences are grammatically correct?02br
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00"You have an obligation 01b00to not be02b00 negative."02br
00"You have an obligation 01b00not to be02b00 negative."02br
00"You have an obligation 01b00to be not02b00 negative."02br
02br
00I think the third sentence is the easiest to understand grammatically.02br
00"You have an obligation to be (01i00insert word/s here02i00)" 01i00not negative.02i02br
02br
00But out of the first two sentences, which is correct? Are they both correct? Is there any difference? Do you agree about the third sentence? And what is this type of grammar situation called so I can look it up?02br
02br
00What are your thoughts?0-