What is the value of the expression: 1-2-3+4-5+6-7+8-.....-2011+2012?
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Originally Posted by Kanwar245 What is the value of the expression: 1-2-3+4-5+6-7+8-.....-2011+2012? 1-2-3+4 = 0 -5 + 6 = 1 -7 + 8 = 1 ....continue OK?
Originally Posted by Kanwar245 What is the value of the expression: 1-2-3+4-5+6-7+8-.....-2011+2012? I think that you have some sign errors in the statement of the question. $\displaystyle \sum\limits_{k = 1}^N {\left( {2k - 1} \right)} = N(N + 1) - N = {N^2}$ $\displaystyle \sum\limits_{k = 1}^N {\left( {2k } \right)} = N(N + 1) = {N^2+N}$
If no sign errors: (2012-4) / 2 - 1004 If -1+2-3+4-5+6....: 2012 / 2 = 1006 (net of 1 per pairs)
No there are no sign errors, so ans is 1004
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