6 thoughts on “Captchas are getting tougher”

  1. the answer is 0.

    This formula, minus the differentiation part = -4*cos(7x).
    The differentiation of the cosinus to x is 28*sin(7x), fill in x=0, and the answer is 0.

  2. If it’s really to detect humans “who the hell knows” “no idea” and “nobody told me there was going to be a quiz” should work just fine.

    Now if it’s to detect math folks, just the one answer. That wasn’t the asserted proof being tested though.

  3. yeah i got zero as well. just using the chain rule,

    28cos(7x-pi/2) evaluated at zero.
    cos(-pi/2) is = 0

  4. Hehe I posted this one a while ago, along with some other very bad captchas.
    Just so you know, here’s the URL that uses that one: http://random.irb.hr/signup.php
    In fact, the math problem is very simple, and this captcha really applies, because it’s for a “quantum random bit generation” service, so only people with math experience will want to use it anyway.

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