document.write( "Question 1143271: Given the arithmetic sequence x,y,30,z,f. Find x+y+z+f?
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Algebra.Com's Answer #764054 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Let the common difference be d. Then these equations are true,\r\n" );
document.write( "so add all the left sides and all the right sides:\r\n" );
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document.write( "                y = 30-d\r\n" );
document.write( "                x = 30-2d\r\n" );
document.write( "                z = 30+d\r\n" );
document.write( "                f = 30+2d\r\n" );
document.write( "-------------------------\r\n" );
document.write( "          y+x+z+f = 120\r\n" );
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document.write( "Notice that there are lots of different possibilities for x,y,z,f.\r\n" );
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document.write( "For example the arithmetic sequence could be \r\n" );
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document.write( "10 20 30 40 50, which have sum 120 with d=10, or\r\n" );
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document.write( "20 25 30 35 40, which also have sum 120 with d=5, or \r\n" );
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document.write( "54 42 30 18 6, which also have sum 120 with d=-12, or any of\r\n" );
document.write( "an infinite number of possible arithmetic sequences.  But the\r\n" );
document.write( "sum will always be 120.  That's interesting!\r\n" );
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document.write( "Edwin
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