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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