Question

not a simple jab of the knife will do it (affirmative)

Answer 1

Yes it does, but there are so many ways to say that that there can be no single "right" answer: He tried everything, He was completely thorough, He cast his gaze everywhere, He looked under every stone... So the only way to logically arrive at an affirmative to that particular sentence is to reuse as many of the original words as possible and simply turn the negative words into positives. no -> all, unturned -> turned

Answer 2

not a simple jab of the knife will do it