29 out of 31, dumb mistake

We got our Calculus midterm retake back this morning. I got 29 out of 31. One question we were asked to sketch a particular function (1/tanh x). I did it right but still got 2/3 on that because I didn't show how I arrived at that.

The first time I stupidly showed the inverse function of tanh x. This time I showed the right graph, the one where tanh x gets dominated by 1/x. But I didn't show work.

For the other mark off, I stupidly changed (cos x / 1 + sin^2 x) into (cos x / cos^2 x) = (1 / cos x) and lost a mark. I had that question right last time so why I thought I needed to further simplify is beyond me, I guess I was trying to be elegant.

I wanted 100%. I wouldn't have gotten it even with the screwup because I thought the sketch was sufficient, but 29 is much better than 14.5. (Twice as good actually ;-)). Too bad it probably won't count for a whole lot. :-(

Written on October 15, 2004