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Question
Evaluate `("n"!)/("r"!("n" - "r")!)` when n = 5 and r = 2.
Solution
`("n"!)/("r"!("n" - "r")!) = (5!)/(2!(5 - 2)!) = (5!)/(2! xx 3!) = (5 xx 4 xx 3 xx 2 xx 1)/(2 xx 1 xx 3 xx 2 xx 1)` = 10
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