1)

The value of (21C110C1)+(21C210C2)+(21C310C3)+.....+(21C1010C10) is


A) 221211

B) 221210

C) 22029

D) 220210

Answer:

Option D

Explanation:

(21C110C1)+(21C210C2)+(21C310C3)+.....+(21C1010C10)

    =   (21C1+21C2+....+21C10)(10C1+10C2+.......+10C10)

12(21C1+21C2+.....+21C20)(2101)

12(21C1+21C2+.....+21C211)(2101)

12(2212)=2201210+1(2101)

   = 220210