totally induction.did you not answer this ?Tahmid Hasan wrote:here's my solution
it is trivial for $k=1$
let us assume that the statement holds for $k=n$,let us also assume that there is such a permutation that the 'blank' square lies on the edge.(ফাঁকা বর্গটা যেন কোণায় থাকে)
now for $k=n+1$,we take $4$ chessboards of $2^n*2^n$ such that after joining them they form a $2^{n+1}*2^{n+1}$ square for which $3$ blank squares are in the middle and the other is at the edge.
now we can cover the $3$ three blank squares with a trimino.
thus our assumption(the additional one too) holds for $k=n+1$
so by mathematical induction it holds for all natural $k$.
BdMO National 2012: Higher Secondary 09, Secondary 10
- nafistiham
- Posts:829
- Joined:Mon Oct 17, 2011 3:56 pm
- Location:24.758613,90.400161
- Contact:
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.
- Tahmid Hasan
- Posts:665
- Joined:Thu Dec 09, 2010 5:34 pm
- Location:Khulna,Bangladesh.
Re: BdMO National 2012: Higher Secondary 09, Secondary 10
well,i did.but forgot to rotate the edge squarenafistiham wrote:
totally induction.did you not answer this ?
বড় ভালবাসি তোমায়,মা
Re: BdMO National 2012: Higher Secondary 09, Secondary 10
প্রশ্নটা বাংলায় একভাবে আর ইংরেজিতে আরেকভাবে ছিল। আমি ফার্স্টে দেখলাম যে বর্গক্ষেত্র থেকে একটা বাদ দেয়ার পর ট্রিমিনো বানানো যাবে আবার দেখাইলাম যে ট্রিমিনো দিয়ে ঐ রকম ক্ষেত্র বানানো যাবে।
Last edited by Phlembac Adib Hasan on Mon Oct 28, 2013 9:50 pm, edited 1 time in total.
Reason: Transliterated
Reason: Transliterated
-
- Posts:5
- Joined:Fri Oct 25, 2013 11:16 pm
Re: BdMO National 2012: Higher Secondary 09, Secondary 10
এমনে করা যায়? প্রতি সাইডে দুইটা করে থাকলে মোট বর্গ ৩টা। তাই $2^2-1$........same at $3\times 3-1$.......so $2^k \times 2^k -1$
$\Longrightarrow 2^{2k} - 1\Longrightarrow (2^k)^2 -1$ ........
$\Longrightarrow 2^{2k} - 1\Longrightarrow (2^k)^2 -1$ ........
Last edited by Phlembac Adib Hasan on Sun Oct 27, 2013 8:25 am, edited 1 time in total.
Reason: Latexed and transliterated
Reason: Latexed and transliterated