Question

# nC0−12nC1+13nC2−...........+(−1)nnCnn+1 = 1/n n

Solution

## The correct option is B Trick : Put n = 1, 2 At n = 1, 1C0 -  121C1 = 1 -  12 =  12 At n =2,  2C0 -  122C1 +  132C2 = 1 - 1 +  13 =  13 which is given by option (c).

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