document.write( "Question 1201548: if P(n,2)=110 find n \n" ); document.write( "
Algebra.Com's Answer #835984 by Theo(13342)\"\" \"About 
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n = 11.
\n" ); document.write( "you get p(n,2) = n! / (n-x)! = 11! / 9! = 11 * 10 * 9! / 9! = 11 * 10 = 110.
\n" ); document.write( "the simple rule is:
\n" ); document.write( "p(n,1) = n
\n" ); document.write( "p(n,2) = n * (n-1)]
\n" ); document.write( "p(n,3) = n * (n-1) * (n-2)
\n" ); document.write( "p(n,4) = n * (n-1) * (n-2) * n-3)
\n" ); document.write( "etc.
\n" ); document.write( "if n is 11, then:
\n" ); document.write( "p(11,1) = 11
\n" ); document.write( "p(11,2) = 11 * 10 = 110
\n" ); document.write( "p(11,3) = 11 * 10 * 9 = 990
\n" ); document.write( "p(11,4) = 11 * 10 * 9 * 8 = 7920
\n" ); document.write( "etc.....
\n" ); document.write( "looking at p(11,4), you get:
\n" ); document.write( "p(11,4) = 11! / (11-4)! = 11! / 7! = 11 * 10 * 9 * 8 * 7! / 7! = 11 * 10 * 9 * 8 = 7920.
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