Another (easy) problem for young people

Paolo902
I'm going to propose you another pretty exercise which can be done by everybody (Steven, this is for you! :wink:).

Find the largest positive integer $n$ for which
$n+10|n^3+100$.

I have solved it, but I am not very sure of the solution I've found. If you wanted to try, I would be grateful.



:wink:

Risposte
Paolo902
"Steven":
Of course :smt053
Thanks for your correction, I edited the message.

See you soon! :wink:


You are welcome. Night.
Thanks.

:wink:

Steven11
Of course :smt053
Thanks for your correction, I edited the message.

See you soon! :wink:

Paolo902
Great, my dear friend, as always.

Just a very very little mistake: pay attention to the divisor (I've written $n+10$ while you wrote $n+1$... you simply forgot some $0$... :wink:)
I got $890$.

Thanks for answering.

Enjoy your evening too. :wink:

Steven11
Here I am :-)

We are looking for the largest $n$ which lets that expression be integer.
It results
$\frac{n^3+100}{n+10}=\frac{n+10^3-900}{n+10}=frac{(n+10)(n^2+100-10n)-900}{n+10}=n^2+100-10n-\frac{900}{n+10}$

So we have to impose that $n+10|900$ and we obtain the major $n$ when
$n+10=900\quad\quad=>\quad\quad n=890$

Did you get the same number?

Bye, have a good evening. :wink:

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