document.write( "Question 1184224: The coefficients of the powers of x in the 2nd, 3rd and 4th term of the expansion $\"+%281+%2B+x%29%5En+\"$ is in arithmetic progression where n is positive integer. Find the number of coefficients of the odd powers of x in the expansion? \n" ); document.write( "

Algebra.Com's Answer #814746 by ikleyn(52835) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( " A quick solution is as follows.\r
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document.write( "Look at the Pascal's triangle in this Wikipedia article\r\n" );
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document.write( "https://en.wikipedia.org/wiki/Pascal%27s_triangle\r\n" );
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document.write( "You will see momentarily that the sought line is the  8th  line for    .\r\n" );
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document.write( "Those coefficients are  7, 21, 35.\r\n" );
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document.write( "The sum of coefficients at odd degrees is HALF of the total sum, which is   = 128.\r\n" );
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document.write( "THEREFORE, the answer to the problem's question is  128/2 = 64.\r\n" );
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