Write the expression nCr+1+nCr−1+2×nCr in the simplest form.
nCr+1+nCr−1+2× nCr=(nCr+1+nCr)+nCr+nCr−1 =n+1Cr+1+n+1Cr {Since nCr+nCr−1=n+1Cr} =(n+1)+1C(r+1)=n+2Cr+1 So, nCr+1+nCr−1+2×nCr=n+2Cr+1