A) 1
B) n
C) \[n+1\]
D) None of these
Correct Answer: C
Solution :
Given expression \[{{(1+x+{{x}^{2}}+.....)}^{2}}\] \[={{[{{(1-x)}^{-1}}]}^{2}}={{(1-x)}^{-2}}\] \[=(1+2x+3{{x}^{2}}+4{{x}^{3}}+....+(n+1){{x}^{n}}+n{{x}^{n-1}}+....)\] Therefore coefficient of \[{{x}^{n}}\] is\[(n+1)\].You need to login to perform this action.
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