If `C(2n,3):C(n,3) ::11:1`, find n.

If " C(n,7)= C(n,5) , find C(n,4) .

If .^(2n)C_(3):^(n)C_(3)=11:1 , find the value of n.

If "^(2n)C_3 : ^nC_2= 12: 1 , find n .

If .^(n)C_(9)=.^(n)C_(7) , find n.

If "^(n-1)C_r : ^nC_r : ^(n+1)C_r= 6:9: 13 , find n and r.

If ""^(n)C_(r ): ""^(n)C_(r+1)=1:2 and ""^(n)C_(r+1): ""^(n)C_(r+2)=2:3 , find n and r.

If .^(n+1)C_(r+1):^(n)C_(r):^(n-1)C_(r-1)=11:6:3 , find the values of n and r.

If .^(2n)C_(3):^(n)C_(2)=44:3 , for which of the following value of r , the value of .^(n)C_(r) will be 15.

If (1 + x)^(n) = C_(0) = C_(1) x + C_(2) x^(2) + …+ C_(n) x^(n) , find the values of the following underset(0leilt j le n)(sumsum)jC_(i)

If (1 + x)^(n) = C_(0) = C_(1) x + C_(2) x^(2) + …+ C_(n) x^(n) , find the values of the following underset(0leile jlen)(sumsum)C_(i)C_(j)