Q14 of 70 Page 379

Find the coefficient of xn in the expansion of (1 + x) (1 – x)n.

To find: the coefficient of xn in the expansion of (1 + x) (1 – x)n.


Formula Used:


Binomial expansion of is given by,



Thus,



Thus, the coefficient of is,


nCn-nCn-1 (If n is even)


-nCn+nCn-1 (If n is odd)


Thus, the coefficient of is,nCn-nCn-1 (If n is even)and -nCn+nCn-1 (If n is odd)


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