I like LJ's new captcha proposal.

[rhu]

Dear LJ,

Great idea! Not only will it cut down on spam, it means I'll only post when I'm really motivated, so the quality of my own blog will improve.

I get -28. Do I get to post? (Although I object to the use of ∂ when it's not multivariate.)

Comments

[jikamens.livejournal.com]

What are you talking about?

[jeffurrynpl.livejournal.com]

I can't see it here but a friend posted it and I said "zero", but now I get 28. I object to the curly d as well.

[530nm330hz.livejournal.com]

It is zero. I got as far as that the derivative is 28*cos(7x-pi/2) in my head and then computed 28 sin(-pi/2). *sigh*

I guess I'm not allowed to post after all.

[530nm330hz.livejournal.com]

Did you follow the link at the word "LJ"?

[jeffurrynpl.livejournal.com]

I should have stuck with my first answer:

4sin(7x - pi/2) = -4cos(7x)
d/dx[-4cos(7x)] = 28sin(7x)
28sin(7*0) = 28sin(0) = 0 and I'm back to zero.

[cazique.livejournal.com]

+1 on the curly d.

[danchall.myvidoop.com (from livejournal.com)]

Click on the hyperlinked LJ in Andrew's post.

[danchall.myvidoop.com (from livejournal.com)]

Thanks to you both for clearing that up. I was not trusting my own results.