SOLUTION: 11p3 evaluate expression

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Question 116152: 11p3 evaluate expression
Answer by jim_thompson5910(21667) About Me  (Show Source):
You can put this solution on YOUR website!
n%21%2F%28n-r%29%21 Start with the given formula



11%21%2F%2811-3%29%21 Plug in n=11 and r=3



11%21%2F8%21 Subtract 11-3 to get 8



Expand 11!
%2811%2A10%2A9%2A8%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%2F8%21



Expand 8!
%2811%2A10%2A9%2A8%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%2F%288%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29



%2811%2A10%2A9%2Across%288%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%29%2F%28cross%288%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%29 Cancel like terms



11%2A10%2A9 Simplify




990 Now multiply 11*10*9 to get 990


So 11 choose 3 (where order does matter) yields 990 unique combinations