Tau

Actually, Duck, there are two errors in your calculations. The first is that the area of a circle is pi * r^2, not 1/2 * pi * r^2. The second is that you have inserted a value of 40 for the time, but you were supposed to insert a value of 40 for the radius. So you should set t=20, giving r=2*20=40.

But since the first error was a factor 1/2, and the second a factor 2, they cancelled each other out, so you got the right answer for the wrong reasons.

Ensign Steve

That is too funny! I saw the right answer at the bottom, and I didn't even bother looking at the work. What a coincidence.

lpetrich

For some reason, doing calculus is practically second nature for me -- both differential and integral.

And though differential calculus is usually very straightforward, the same cannot be said of integral calculus much of the time. Even though integral = inverse of differential (!)

Big Spoon

just wait 'til you try analytic calculus! Riemann integrals are not pretty...

Worldtraveller

Hey, don't scare the poor guy!! And Riemann sums are nasty, but not THAT bad. :P

Aerospace Engineers: We do more math before 9 am than most people do all day.

ex-xian

I've got that this fall.

Ensign Steve

Is this something a business major needs to know? I'm an accountant for pete's sake. All I ever use at work is plus! Well, sometimes minus.

ex-xian

Sorry, I guess math nerds get carried away sometimes. But if you take a second semester of calc you'll be able to understand compound interest.

Duck!

Nuts.

When I did it first I used pi*(r^2) but got 80pi as the answer, so I thought that my circle formula was wrong. So I "corrected" it.


Duck!

Lobstrosity

Ah yes, the time-honored technique of sneaking constants and minus signs into your work such that you get the answer you want.