document.write( "Question 1207619: I have $3$ different mathematics textbooks, $2$ different psychology textbooks, and $2$ different chemistry textbooks. In how many ways can I place the $7$ textbooks on a bookshelf, in a row, if all three mathematics textbooks must be together? \n" ); document.write( "

Algebra.Com's Answer #845590 by ikleyn(52788) $\"\"$ $\"About$

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\n" ); document.write( "I have 3 different mathematics textbooks, 2 different psychology textbooks,
\n" ); document.write( "and 2 different chemistry textbooks. In how many ways can I place the 7 textbooks
\n" ); document.write( "on a bookshelf, in a row, if all three mathematics textbooks must be together?
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document.write( "We start the solution, considering 3 Math textbook as one object. \r\n" );
document.write( "We have then 5 different objects, at all, and 5! = 120 possible\r\n" );
document.write( "permutations for them.\r\n" );
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document.write( "Then we multiply 5! by 3! = 6, the number of permutations inside the set of 3 Math textbook.\r\n" );
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document.write( "Thus we come to the \r\n" );
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document.write( "ANSWER.  There are 5!*3! = 120*6 = 720 different arrangements of the textbooks \r\n" );
document.write( "         on a bookshelf under the given restriction.\r\n" );
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