Difference between revisions of "2016 AMC 12A Problems/Problem 1"

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<cmath>\frac{11\cdot 10\cdot 9!}{9!} - \frac{10\cdot 9!}{9!}</cmath>
 
<cmath>\frac{11\cdot 10\cdot 9!}{9!} - \frac{10\cdot 9!}{9!}</cmath>
 
<cmath>(11\cdot 10) - 10</cmath>
 
<cmath>(11\cdot 10) - 10</cmath>
<cmath>\boxed{\textbf{(b) } \, 100}</cmath>
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<cmath>\boxed{\textbf{(B) } \, 100}</cmath>
  
 
==See Also==
 
==See Also==
 
{{AMC12 box|year=2016|ab=A|before=First Problem|num-a=2}}
 
{{AMC12 box|year=2016|ab=A|before=First Problem|num-a=2}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 22:53, 3 February 2016

Problem

What is the value of $\frac{11!-10!}{9!}$?

$\textbf{(A)}\ 99\qquad\textbf{(B)}\ 100\qquad\textbf{(C)}\ 110\qquad\textbf{(D)}\ 121\qquad\textbf{(E)}\ 132$

Solution

\[\frac{11!-10!}{9!} = \frac{11!}{9!} - \frac{10!}{9!}\] \[\frac{11\cdot 10\cdot 9!}{9!} - \frac{10\cdot 9!}{9!}\] \[(11\cdot 10) - 10\] \[\boxed{\textbf{(B) } \, 100}\]

See Also

2016 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
First Problem
Followed by
Problem 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

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