Answer :
nCr+1 + nCr-1 + 2 
nCr
= (nCr+1 + nCr) + (nCr + nCr-1)
⇒ (nCr + nCr-1 = n+1Cr)
= n+1Cr+1 + n+1Cr
⇒ (nCr + nCr-1 = n+1Cr)
= n+2Cr+1
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