[koito17]

The question I got was surprisingly simple: it asked to find "the least real root of the polynomial p(x) = (x+5)(x-4)(x+1)". A determined attacker can quickly hack together something with Tesseract and feed it into even GPT-3.5 to get the correct answer to questions like these.

I guess that means the captcha is doing its job, since running LLMs isn't very cheap or scalable. But any harder problem means you start filtering a significant chunk of human users. Based on the other replies to your comment, it seems that the questions at their current difficulty already stop a lot of human users, yet allow a determined attacker with the setup I described pass through easily.

[explaininjs]

I'm not sure how you'd determine the least real root to that, given all three have equally zero imaginary component.

[wnoise]

They of course the minimum out of the set of the real roots.

[cwillu]

I suppose the square root of negative infinity has the property of being unreal in several distinct ways, but yeah, the least real? I dunno /s