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Question
15C8 + 15C9 – 15C6 – 15C7 = ______.
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Solution
15C8 + 15C9 – 15C6 – 15C7 = 0.
Explanation:
15C8 + 15C9 – 15C6 – 15C7 = 15C15–8 + 15C15–9 – 15C6 – 15C7 ......[∵ nCr = nCn–r]
= 15C7 + 15C6 – 15C6 – 15C7
= 0
Hence, the value of the filler is 0.
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