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Question
Find n if 23C3n = 23C2n+3
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Solution
23C3n = 23C2n+3
We know that if nCx = nCy, then x = y or x + y = n
∴ 3n = 2n + 3 or 3n + 2n + 3 = 23
∴ n = 3 or 5n = 20
∴ n = 3 or n = 4.
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