document.write( "Question 1110010: The xth, yth, and zth terms of a sequence are X,Y,Z respectively. Show that if the sequence is arithmetic then X(y-z) + Y(z-x) + Z(x-y)=0.\r
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Algebra.Com's Answer #725012 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "To avoid getting capital and small letters confused I will \r\n" );
document.write( "let p=x, q=y, and r=z.  Then the problem is:\r\n" );
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\n" ); document.write( "The pth, qth, and rth terms of a sequence are X,Y,Z respectively. Show that
\n" ); document.write( "if the sequence is arithmetic then X(q-r) + Y(r-p) + Z(p-q)=0.
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document.write( "Let the sequence be arithmetic, with first term a \r\n" );
document.write( "and common difference d, then by the formula for nth term, \r\n" );
document.write( "we have these three equations:\r\n" );
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document.write( "\"system%28a+%2B+%28p-1%29d+=+X%2Ca+%2B+%28q-1%29d+=+Y%2Ca+%2B+%28r-1%29d+=+Z%29\"\r\n" );
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document.write( "Solve the first and second equations for d\r\n" );
document.write( "\"d=%28Y-X%29%2F%28q-p%29\"\r\n" );
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document.write( "Solve the first and third equations for d\r\n" );
document.write( "\"d=%28Z-X%29%2F%28r-p%29\"\r\n" );
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document.write( "Since both expressions equal d, they are equal to each other\r\n" );
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document.write( "\"%28Y-X%29%2F%28q-p%29\"\"%22%22=%22%22\"\"%28Z-X%29%2F%28r-p%29\"\r\n" );
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document.write( "Cross-multiply:\r\n" );
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document.write( "\"%28Y-X%29%28r-p%29=%28Z-X%29%28q-p%29\"\r\n" );
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document.write( "\"Yr-Yp-Xr%2BXp+=+Zq-Zp-Xq%2BXp\"\r\n" );
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document.write( "\"Yr-Yp-Xr+=+Zq-Zp-Xq\"\r\n" );
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document.write( "\"Xq-Xr%2BYr-Yp%2BZp-Zq=0\"\r\n" );
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document.write( "\"X%28q-r%29+%2B+Y%28r-p%29+%2B+Z%28p-q%29+=+0\"\r\n" );
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document.write( "Edwin
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