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I liked this simple calculus exercise

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Re: I liked this simple calculus exercise

#101
post #81

Earlier quoted context omitted.

Also a good question to test intuition is being asked to sketch e^sin(x) and sin(e^x).

TCL, package require math, a few lines of puts writting to a file and then gnuplot that.

That's one of many ways to check one's answer. The whole point is to be able to intuit a rough sketch of what the graph should be, not to use software tools to build a pixel-perfect render of the plot.

Re: I liked this simple calculus exercise

#102

Earlier quoted context omitted.

Also a good question to test intuition is being asked to sketch e^sin(x) and sin(e^x).

Intuition tells me e^sin(x) would look similar to an ordinary sinusiod, except its range would be between e^-1 and e, and its shape would not be smooth as a sinusiod. I have no idea what the shape would look like, and I'm a visual learner when it comes to mathematics. I think most of these questions are not measuring intuition per se, but rather has the tested person previously seen such functions plotted on a graph.…

It wouldn’t look too dissimilar to a standard sinusoid, just shifted upwards a bit. In the range [-1, 1], e^x is reasonably similar to 1 + x.

Re: I liked this simple calculus exercise

#103
post #64

Here's another exercise (resp. exam question) that tests understanding: given a sketch of a curve in a graph, roughly sketch the derivative (or integral). The number of otherwise good students who go "but I can't do the derivative without the formula?" suggests we need more questions like this.

The problem is that most teachers cannot come up with questions that go outside the small number of cases which the student trains on. I mean, coming up with fundamentally new questions is very hard work once the low hanging fruit is gone.

That or the point of the class is to prepare for a test set by someone other than the teacher (such as in UK A-levels), where you know the questions will mostly be of the form "derivative of 3x^2-5x+1" or similar.

Re: I liked this simple calculus exercise

#104
post #82

Here's another exercise (resp. exam question) that tests understanding: given a sketch of a curve in a graph, roughly sketch the derivative (or integral). The number of otherwise good students who go "but I can't do the derivative without the formula?" suggests we need more questions like this.

I learned basics of calculus as a teenager making animations with a pirated copy of Adobe After Effects. It’s a motion graphics package where you can animate any property of an element over time using both absolute values and velocity curves (i.e. the derivative). It shows both curves next to each other, so you can tweak either and see how the other changes. Seeing graphics animate according to a derivative that you…

This is a good idea. If I ever teach basic calc again, I will use it. Thanks!

(The last time I taught math was vector calc 4 years ago. The last time I taught the first semester intro to calc was 30 years ago OMG-LOL.)

Re: I liked this simple calculus exercise

#105

Current Calc 2 student here. I would be braindead approaching this problem honestly, I don't think I'd even know how to begin; I'm hoping that's normal. Why would the exponent be equal to x/2 - floor(x/2) be equal to x/2 on the interval [0, 2)? And how does the graph of x/2 - floor(x/2) imply anything about the behavior of e^(x/2 - floor(x/2))? I'm hoping I just haven't learned enough yet?

calc 2 was the hardest for me, and anecdotally many others. hang in there!

Re: I liked this simple calculus exercise

#106
post #72

Earlier quoted context omitted.

Seems a little much for a regular calculus class. Wouldn't that fit better in a complex analysis class?

No, this would be a good exercise for first-year calculus. It's a very reasonable question, nothing out of the ordinary.

In fact, I was taught the graphical intuition via a few days of these sorts of exercises, before being introduced to the formulas. It worked really well, at least for 9th grade students in an acceleration program at the University of Minnesota (UMTYMP).

Re: I liked this simple calculus exercise

#107

Earlier quoted context omitted.

Also a good question to test intuition is being asked to sketch e^sin(x) and sin(e^x).

Intuition tells me e^sin(x) would look similar to an ordinary sinusiod, except its range would be between e^-1 and e, and its shape would not be smooth as a sinusiod. I have no idea what the shape would look like, and I'm a visual learner when it comes to mathematics. I think most of these questions are not measuring intuition per se, but rather has the tested person previously seen such functions plotted on a graph.…

You're basically right. Here's the graph: https://www.desmos.com/calculator/lf3xerswdy

Re: I liked this simple calculus exercise

#108

Here's another exercise (resp. exam question) that tests understanding: given a sketch of a curve in a graph, roughly sketch the derivative (or integral). The number of otherwise good students who go "but I can't do the derivative without the formula?" suggests we need more questions like this.

I remember there being a distinct lack of "closing the loop" on concepts in university math.

Day 1 of the class: The derivative calculates the slope of a function

Day 2: The integral calculates the area under the curve of the function

Days 3-89: Rote exercises deriving and integrating increasingly obscure functions

Day 90: Final Exam

Spending a few days at the end re-exploring the "big picture day-1" to tie together all of the various strands of knowledge you accumulate over the semester would have made all of it so much more effective.

Re: I liked this simple calculus exercise

#109

Slightly off-topic: didn't know what ⌊x/2⌋ is Google: x squared (???) GPT: The expression ⌊x/2⌋ represents the greatest integer that is less than or equal to x/2. It is called the floor function of x/2. For example, if x=5, then ⌊x/2⌋ = ⌊5/2⌋ = 2. If x is an even integer, then ⌊x/2⌋ = x/2. If x is an odd integer, then ⌊x/2⌋ = (x-1)/2.

I expect Google is stripping the ⌊ ⌋ brackets out as punctuation in the search, so that you're effectively only searching for "x2", hence the "x squared" results.

Re: I liked this simple calculus exercise

#110
post #64

Here's another exercise (resp. exam question) that tests understanding: given a sketch of a curve in a graph, roughly sketch the derivative (or integral). The number of otherwise good students who go "but I can't do the derivative without the formula?" suggests we need more questions like this.

The problem is that most teachers cannot come up with questions that go outside the small number of cases which the student trains on. I mean, coming up with fundamentally new questions is very hard work once the low hanging fruit is gone.

Sounds like something ChatGPT could do quite quickly though.
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