1.

`nCr + 2. nC(r-1) + nC(r-2) = (n+2)Cr (2

Answer» Here, we will use the property of binomial coefficients,
`n_(C_r) + n_(C_(r-1)) = (n+1)_(C_r)`
`L.H.S. = n_(C_r)+2*n_(C_(r-1))+n_(C_(r-2))`
`= n_(C_r)+n_(C_(r-1))+n_(C_(r-1))+n_(C_(r-2))`
Using the above property,
`=(n+1)_(C_r)+(n+1)_(C_(r-1))`
Again using the above property,
`=(n+2)_(C_r) = R.H.S.`


Discussion

No Comment Found

Related InterviewSolutions