document.write( "Question 1178123: There are 10 identified points on a number line. How many possible rays can
\n" ); document.write( "be drawn using the given points? \n" ); document.write( "
Algebra.Com's Answer #807288 by ikleyn(52781)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            Tutor @amarjeeth is not right,  and his answer is not correct.\r
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\n" ); document.write( "\n" ); document.write( "If to accept the conception,  that a ray is determined by a pair of points,\r
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\n" ); document.write( "\n" ); document.write( "and the number of different pairs and different rays will be  10*9 = 90  (not  45  (!) ).\r
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\n" ); document.write( "\n" ); document.write( "In this problem,  we work with  PERMUTATIONS  of  10  points, taken  2  at a time,  and  NOT  with the  COMBINATIONS  (!).\r
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\n" ); document.write( "\n" ); document.write( "Again,  the order of points in pairs  DOES  MATTER  in this problem (!).\r
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\n" ); document.write( "\n" ); document.write( "Solved  (correctly).\r
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