MathematicsEasy98×since 2002Q4809If nCr{}^n{C_r}nCr denotes the number of combination of n things taken r at a time, then the expression nCr+1+nCr−1+2 × nCr\,{}^n{C_{r + 1}} + {}^n{C_{r - 1}} + 2\, \times \,{}^n{C_r}nCr+1+nCr−1+2×nCr equalsA n+1Cr+1\,{}^{n + 1}{C_{r + 1}}n+1Cr+1Bn+2Cr{}^{n + 2}{C_r}n+2CrCn+2Cr+1{}^{n + 2}{C_{r + 1}}n+2Cr+1D n+1Cr\,{}^{n + 1}{C_r}n+1CrCheck answerSkip