1 Crore+ students have signed up on EduRev. Have you? 
If C_{r} stands for ^{n}C_{r}, then the sum of the series where n is an even positive integer, is equal to (1986  2 Marks)
∵ n is even, let n = 2m then
....(1)
[Using C_{r }= C_{n– r}]
....(2)
Adding (1) and (2):
Now keeping in mind that if n is even, then
∴ we get
If equals (1998  2 Marks)
Let
[∵ ^{n}C_{r} = ^{n}C_{nr}]
= na_{n} – b
132 docs70 tests

Use Code STAYHOME200 and get INR 200 additional OFF

Use Coupon Code 
132 docs70 tests





