Mark the correct alternative in the following :

If rth term is the middle term in the expansion of , then term is


Given:




Total terms = n+1 = 21


Mid term = 21/2 = 11th term


For k= 10,it is rth term.


So (r+3)th term = 11th term


k=13


T14




= -20C13 x. 2 -13


= -20C7 x. 2 -13

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