The coefficient of `x^4` in the expansion of `(1+x+x^2+x^3)^n` is (A) `^nC_4` (B) `^nC_4+^nC_2` (C) `^nC_4+^nC_2+^nC_4.^nC_2` (D) `^nC_4+^nC_2+^nC_1.^nC_2`

If .^nC_8=^nC_2 , find .^nC_2

If "^nC_10 = ^nC_5 find "^nC_14

If .^nC_9=^nC_8 find .^nC_17

If "^nC_5= ^nC_12 find n.

Find n if "^nC_12 = ^nC_8

The co-efficient of x' in the polynomial (x+2nC_(0),)(x+2nC_(2))(x+2nC_(4))...(x+2nC_(2n)) is

"^mC_1=^nC_2 , then -

If .^nC_12=^nC_8 , find .^nC_17 and ^22C_n

m points on one straight line are joined to n points on another straight line. The number of points of intersection of the line segments thus formed is (A) ^mC-2.^nC_2 (B) (mn(m-1)(n-1))/4 (C) (^mC_2.^nC_2)/2 (D) ^mC_2+^nC_2