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Thursday August 21, 2008

It Could Be Worse

Over the last four years as I've been doing this blog, I've had a few people complain that the simple math question you have to answer when posting a comment is annoying.

Well it could be worse.

(taken from Worst Captchas of All Time).

[Technorati Tag: Humor]

( Aug 21 2008, 05:32:58 AM PDT ) [Listen] Permalink Comments [6]

Comments:

The problem isn't too hard (remeber that Chain Rule!), except that they have specified the lower-bound of the definite integral, but not the upper-bound. Am I missing something?

Posted by Tom Dison on August 21, 2008 at 08:19 AM PDT #

My answer: 42. :-)

It does have potential though: Anyone who gets the correct answer is clearly NOT human. The rest of us could continue to comment. Nothin' personal Tom. ;-)

Posted by joanie on August 21, 2008 at 12:52 PM PDT #

It isn't the integral. It is the derivative, evaluated at X=0.

And while 42 is undoubtedly the correct answer... the right guesses with SIN and COS and values involving pi/2 are 1 and 0 sorts of things. Given the 4 and 7 floating around, 4, 7, and 28 would be reasonable guesses, too. Zero is right in this case. And I believe the reason this is a test of whether you are human is that any sensible human would guess. (Well, actually, most sensible humans would just skip it, but imagine you actually really really cared about getting it right but didn't have either the time or ability to figure it out.)

For those of you who care (OK, I've lost everyone)...

The derivative of sin is cos.

d(sin(u))/dx = cos(u)*du/dx

d(sin(7*x-pi/2))dx = cos(7*x-pi/2)d(7*X-pi/2)/dx

= 7*cos(7*x-pi/2)

evaluate at x=0 and you get 7*cos(-pi/2)

Strictly speaking I've left out the "4*" and the full answer is 28*cos(-pi/2). But it doesn't matter as cos(-pi/2) is 0.

Oh, and by the way, I'm one of the people who complained to Rich about the stupid math problem. And, no, I wouldn't have been happier with this much more complicated one. (Tonight I have to add 9 and 77. Anyone want to help me with that?)

Posted by Steve Uhlir on August 21, 2008 at 08:24 PM PDT #

BTW
It would be good to have ability to change complication of such questions.
It helps to manage of commenter auditory.
:)

Posted by ahot on August 23, 2008 at 10:24 AM PDT #

Try this URL instead :
http://www.scribd.com/doc/4964973/Worst-Captchas-of-All-Time
. Your link seems to be dead.

Posted by Robert Sugg on September 15, 2008 at 07:40 PM PDT #

Adjusted. Thanks Robert.

Posted by Rich Burridge on September 15, 2008 at 07:52 PM PDT #