k.C₀+k².C₁/2+K². C₂/3+.…………+kⁿ⁺¹.C_n/n+1 =

If x+y=1, then ².ⁿC_rx^r.y^n-r =

2.C₂+6.C₃+12.C₄+……….+n(n-1)C_n =

If the sum of the coefficients of (1+2x)ⁿ is 6561, then the greatest coefficient is

If (1+x+x²)ⁿ =Σ_{r=0²ⁿ r}x^r then a₀+a₂+a₄+……….+a_2n=