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What is C(n, r) + 2C(n, r – 1) + C(n, r) equal to? a. C(n + 1, r) b. C(n –1, r + 1) c. C(n, r + 1) d. C(n + 2, r) |
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Answer» Correct option d. C(n + 2, r) Explanation: nrC + n(r - 1)C + n(r - 2)C = (n + 1)rC + (n + 1)(r - 1)C = (n + 2)rC |
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