Top 10 Worst Captchas

IT Management and Cloud ^ | 16 February 2008 | John Willis

[ShadowAce]

[Dr. Sivana]

Doesn't that one have a division by zero problem?

[cripplecreek]

I saw the worst one EVAH yesterday. Didn’t think of doing a screengrab.

[ShadowAce]

No--that first symbol you see is not division, but derivation.

Basically, it is saying "Take the derivative of the follow equation with respect to x.

[Slings and Arrows]

Doesn't that one have a division by zero problem?

No, but the expression does evaluate to zero.

[ShadowAce]

LOL! It’s been almost 20 years since I’ve done derivatives. I couldn’t figure it out off the top of my head.

[krb]

Oh man. I got 28.

[NVDave]

The first symbol is a “partial derivative” of the expression in the brackets, with the expression in the brackets evaluated with x as zero.

If I can kick-start my sleep-deprived brain, I think the final result comes out as:

7*x = 0,

which leaves us with 4 * sin(-pi/2), and doing a quick radian->degree conversion, we have sin(270 degrees) which is -1, so we have 4 * -1 which is -4.

The derivative of any constant is 0, and since -4 qualifies, the sum total of that mess is zero, zed, zip, bupkiss, nil, 0.

[krb]

Don’t you have to take the derivative before you evaluate?

so you get 4 * 7 * cos (7*x) where x = 0, so you get 28, right?

[Dr. Sivana]

It has been 26 years since I took Calculus, but I always thought that one of those tall ∫ things was usually involved in derivatives.

[NVDave]

With the notation on the right of |x=0, I believe you have to start evaluating from the inside to arrive at what you’re taking the derivative of.

[krb]

Those tall things are anti-derivatives, or integrals.

[rimtop56]

Maybe if you get it right, you show you are a computer. If you miss it, you prove you are a human.

[Slings and Arrows]

No, that’s for integrals.

[NVDave]

Those are integrals, but they usually had a notation like “d/dx” on the end of the integral, which meant that you were integrating with respect to the derivative of x, or “d/dt” which means you’re integrating with respect to the derivative of time, etc.

[MortMan]

That’s integration - the opposite of derivation.

[Dr. Sivana]

Thanks for the correction. I guess I am not qualified to be a human on that web site!

[Future Snake Eater]

That should be the derivative of -28, which is zero.

[NVDave]

I just remembered Wolfram released their math “google” page, which allows you to do amazing stuff on the fly.

Here’s the result:

http://www.wolframalpha.com/input/?i=partial+derivative+of+%5B4+*+sin%287*x+-+pi%2F2%29%5D%7Cx%3D0