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teerasak · (This post was last modified: 06-02-2020 04:28 AM by teerasak.)

I tried to evaluate the following statement and got the message that the integral in limit is not implemented.

[Image: Cap1.png]

Then I tried to find approximate of the limit by using large number of n, still cannot get the result.

[Image: cap3.png]

So could you please add this feature so that the calculator can do this?

TI NSpire provides limit of integral as Infinity. When testing numerically by putting large n, the integration result give a large number - so the correct should be infinity.

parisse · 06-02-2020, 02:01 PM

Interesting, I wonder how they do that, because the limit is 0. Make one integration by part by integrating sin(n*pi*x), this will give a factor 1/n, and that will tend to 0 as n->infinity.
Probably they are messed up with the exponential that is too large to be represented by a floating point value at 4*pi.

teerasak · 06-03-2020, 06:17 PM

Thank you,Parisse. In fact, I don’t have the answer for this question and I can’t find indefinite integral form of that. So I tried with calculator, but no luck.

parisse · 06-04-2020, 06:05 AM

The next question is how did you get this exercice ? I mean, if you don't have any clue of the answer, trying with the calc is one way to go. But it seems this exercice was taylored to make this experimental approach fail.

teerasak · 06-04-2020, 06:26 AM

I got it from facebook group in math. The time I got has no solution yet, and I didn’t save it. I don’t have the answer, so I tried with the calculator.

I did try with Wolfram and it could not give the answer too. Surprisingly TI nspire could do, but as you mentioned, i’m suspecting it gave wrong answer.

parisse · 06-05-2020, 05:42 AM

(06-04-2020 06:26 AM)teerasak Wrote: I got it from facebook group in math. The time I got has no solution yet, and I didn’t save it. I don’t have the answer, so I tried with the calculator.

I did try with Wolfram and it could not give the answer too. Surprisingly TI nspire could do, but as you mentioned, i’m suspecting it gave wrong answer.

Suspect is not the right word, because it's easy to *prove* that the TI nspire gives a wrong answer here: as I explained previously, the right answer is 0.