Comment on MS new captcha: Why did it have to be that hard!?!?

• morgunkorn@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

  no, you need to derivate the f(x) function twice because the last line asks for f"(x). you do that by taking down the exponent in front of each power of the polynomial and decreasing the power by one each time you derivate.

  So for the 13x³: derived once it becomes 3 times 13 x² derived once, equals 39x². Derived a second time, it is 2 times 39x, so 78x.

  The x is given when finding the correct pattern that matches the missing symbol in the first part of the problem, being the dot, so 52. I explained how you find this in a comment somewhere up here :)

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  • jaybone@lemmy.world ⁨1⁩ ⁨week⁩ ago

    Pretty sure 78x + 22 is f double prime of x. So f’’(x) + x simplifies to 79x + 22.

    I found the other posts about XOR for solving the visual puzzle.

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    • morgunkorn@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

      ah ok you’re adding the final x directly to the polynomial, that’s fine then, yes

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  • letsgo@lemm.ee ⁨1⁩ ⁨week⁩ ago

    f’‘(x) is 78x+22 but the question asks what number is f’'(x) + x, hence 79x+22.

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    • morgunkorn@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

      yeah, i just did the derivative first and added that last x at the end, same result

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