# Gee, how stupid.

1. Mar 7, 2008

### octahedron

So in a calc 2 exam, you gloss over all the derivatives questions and get to integration and series. You get the really tough integrals, but you miss the grade-boosting derivative question (10%/100)?! So I've never gotten lower than 95% on a math midterm, but now I'm getting 85%~. Look at how stupid I was when I saw this question:

Find y' of $$(x^{2} + 3x)^{ln(x)}$$. If I told you I used power rule, how'd that bode for me as a math major?

2. Mar 7, 2008

### Staff: Mentor

Art is a nice major - not meant to denigrate Art....

3. Mar 7, 2008

### Schrodinger's Dog

That's not an easy derivative. Should of used the chain rule first though, then it looks like some sort of product, I had a quick go, but I think it might take a while. And anyway quit beating yourself up everyone makes mistakes.

4. Mar 7, 2008

### octahedron

Oh, I used the chain rule along with the power rule. My point was that I treated ln(x) as a constant by somehow overlooking the x in ln, ha ha. Definitely looking at art history for a change.

Last edited: Mar 7, 2008
5. Mar 7, 2008

### Schrodinger's Dog

Hehe, yeah that's pretty dumb, but nobody's perfect.

The power rule is the chain rule for powers, I got what you meant.

Oh by the way x is not a constant. :tongue:

6. Mar 7, 2008

### Kurdt

Staff Emeritus
x is a constant pain in the ass. I'm always having to solve for x. Why can't x solve for itself?

7. Mar 7, 2008

### Astronuc

Staff Emeritus
Don't take it so hard. In cases like this, I have just worked out the problem and shown it to the teacher so that the teacher realizes I know how to work the problem. I'm sure I've made exactly the same mistake with regard to a variable exponent.

Sometimes one has to think in terms of f(x)g(x).

8. Mar 7, 2008

### tkjacobsen

Then one just has to remember that

$$f(x)^{g(x)} = \exp(g(x)\ln(f(x)))$$

9. Mar 7, 2008

### Oerg

sometimes, one of the techniques which I utliize whenever I take exams is this:

Skip over any questions which you have to think for more than about 1-2 mins. This ensures that you do not spend needless time over questions that you MAY not be able to solve. Instread, when you get back to these questions, you should have plenty of time to solve them and this psychological advantage will help you calm your nerves whereas if you were to solve the question head on, you will get more nervous as you feel that you are running out of time and spending too much time on one question.

10. Mar 7, 2008

### Kurdt

Staff Emeritus
My anxiety levels in exams were terrible (as they are everywhere). I used to go in rush as much as I could in the 30 minutes and then run away :rofl:. I'm amazed I passed anything.

Last edited: Mar 7, 2008
11. Mar 7, 2008

### lisab

Staff Emeritus
Excellent test strategy. It's a confidence booster to get two or three easy problems done, then you can relax and concentrate on the rest of the exam.

12. Mar 7, 2008

### tkjacobsen

I did that to my electormagnetism exam. I ended up just skipping all problems, and just started over again...

13. Mar 7, 2008

### lisab

Staff Emeritus
:rofl:

14. Mar 7, 2008

### Poop-Loops

Laugh if you will, I did the exact same thing on more than one occasion.

Last test, there were only 3 problems.

15. Mar 7, 2008

### lisab

Staff Emeritus
Oh I remember those days very clearly. There aren't any "gimmees" on upper division E&M exams!

16. Mar 7, 2008

### Moonbear

Staff Emeritus
Yeah, what a useless variable. It should start pulling its own weight and solving some of its own problems.

:rofl: Indeed, that advice only works up to a certain level. When you get 6 questions and 4 hours for an exam, skipping the hard questions while looking for some you can quickly complete in 1-2 min isn't a very effective strategy anymore.

octahedron, there's no point beating yourself up over it. Everyone has made a fatal exam mistake that lost them a lot of points for reading carelessly at sometime in their life.

17. Mar 7, 2008

### octahedron

I'm definitely not beating myself over this again. :p
I did that in my physics midterm (baby E&M), and it served me well. Somehow during my math midterms I get too excited for my own good and decide to get to the "real" questions quickly and skip all the fluff (the derivatives -- two of them, and accounting for 20% -- were fluff, but I somehow regret not second guessing myself on the second one -- it seemed over too quickly).