SOLUTION: in how many ways can nine students be seated in a row containing nine desks if two students must not be seated next to each other? my thinking is 9!2! because u have 9 students but

Question 548056: in how many ways can nine students be seated in a row containing nine desks if two students must not be seated next to each other? my thinking is 9!2! because u have 9 students but 2 of them have a stipulation ...
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
there are 9! ways with no stipulation

if you view the pair as a unit; there are 8 positions for the pair,
___ times 2 for the arrangement of the pair,
___ times 7! for the arrangement of the other students

9! - [(8)(2)(7!)] ___ 9! - [(8!)(2)] ___ [(9)(8!)] - [(2)(8!)] ___ (7)(8!)
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