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Question
Choose the correct alternative:
`""^(("n" - 1))"C"_"r" + ""^(("n" - 1))"C"_(("r" - 1))` is
Options
`""^(("n" + 1))"C"_"r"`
`""^(("n" - 1))"C"_"r"`
nCr
`""^"n""C"_("r" - 1)`
Solution
nCr
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