Which of the following identities holds for all integers and ?

MATHEMATICS · Single correct · CBSE · Mathematics · Binomial Theorem · Binomial Theorem

Problem

Which of the following identities holds for all integers n≥1n \ge 1 and 1≤r≤n1 \le r \le n? (a) nCr+nCr−1=n+1Cr+1{}^{n}C_{r}+{}^{n}C_{r-1} = {}^{n+1}C_{r+1} (b) nCr+nCr−1=n+1Cr{}^{n}C_{r}+{}^{n}C_{r-1} = {}^{n+1}C_{r} (c) nCr+nCr−1=nCr+1{}^{n}C_{r}+{}^{n}C_{r-1} = {}^{n}C_{r+1} (d) nCr+nCr−1=n+1Cr−1{}^{n}C_{r}+{}^{n}C_{r-1} = {}^{n+1}C_{r-1}

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