document.write( "Question 1146059: For a set of two elements find the number of different subsets of 1 element. Use row 2 of pascals triangle to find the answer. \n" ); document.write( "
Algebra.Com's Answer #767336 by Edwin McCravy(20064)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "It's just like question 1146008 that I answered so I'll just copy and paste\r\n" );
document.write( "from it.  That question there was:\r\n" );
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document.write( "\"suppose 5 fair coins are tossed. use pascals triangle to find the number of\r\n" );
document.write( "ways obtaining exactty 4 heads.\"\r\n" );
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document.write( "A coin has two \"elements\", a 'head' and a 'tail'. \r\n" );
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document.write( "Remember the rule I gave you: \r\n" );
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document.write( "Suppose N fair coins are tossed. To find the number of ways of\r\n" );
document.write( "obtaining exactly R heads, go down to the (N+1)st row, and then\r\n" );
document.write( "go right to the (R+1)st number.\r\n" );
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document.write( "Your problem here is \r\n" );
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document.write( "Suppose 2 fair coins are tossed. To find the number of ways of\r\n" );
document.write( "obtaining exactly R heads, go down to the 3rd row, and then\r\n" );
document.write( "go right to the 2nd number.\r\n" );
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document.write( "But wait! The difficulty here is the fact that your teacher and book\r\n" );
document.write( "leaves off the top \"1\" from Pascal's triangle (which makes it\r\n" );
document.write( "not be a \"triangle\" but a trapezoid!!!) but it changes the rule \r\n" );
document.write( "from the (N+1)st row to the Nth row.  But it doesn't change the \r\n" );
document.write( "rule for the (R+1)st number in that row. [Your teacher should \r\n" );
document.write( "call it \"Pascal's trapezoid\" instead of \"Pascal's triangle\". lol]\r\n" );
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document.write( "So your Pascal's \"triangle\" looks like this trapezoid:\r\n" );
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document.write( "                    1     1\r\n" );
document.write( "                 1     2     1\r\n" );
document.write( "              1     3     3     1\r\n" );
document.write( "           1     4     6     4     1\r\n" );
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document.write( "with the top \"1\" lopped off.  So your rule is\r\n" );
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document.write( "Suppose N fair coins are tossed. To find the number of ways of\r\n" );
document.write( "obtaining exactly R heads, go down to the Nth row, and then\r\n" );
document.write( "go right to the (R+1)st number.\r\n" );
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document.write( "You will use N as 2 and R as 1.  So it will be the same as\r\n" );
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document.write( "Suppose 2 fair coins are tossed. To find the number of ways of\r\n" );
document.write( "obtaining exactly R heads, go down to the 2nd row, and then\r\n" );
document.write( "go right to the 2nd number.  I made that number red above.\r\n" );
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document.write( "Edwin
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