document.write( "Question 1169540: (A)lex, (B)rian, (C)laire, and (D)ana, have 4 tickets to the play. Use the fundamental counting principal and the slot (blank) method to answer the question\r
\n" ); document.write( "\n" ); document.write( "In how many ways can they be arranged so that Alex and Brian are not sitting next to each other? \n" ); document.write( "
Algebra.Com's Answer #794330 by ikleyn(52781)\"\" \"About 
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document.write( "The idea is to subtract from the total number of all possible permutations of 4 objects \r\n" );
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document.write( "the number of permutations where persons A and B are together.\r\n" );
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document.write( "The total number of permutations of 4 objects is 4! = 4*3*2*1 = 24.\r\n" );
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document.write( "To determine the number of permutations of 4 persons where A and B are together, we consider A and B as one object,\r\n" );
document.write( "but we shoud account that A and B can sit in two different configurations (AB) and (BA).\r\n" );
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document.write( "Therefore, the answer to the problem's question is  \r\n" );
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document.write( "    4! - 2*3! = 24 - 2*6 = 24 - 12 = 12.\r\n" );
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