A) 826
B) 816
C) 822
D) none of these
Correct Answer: B
Solution :
[b] \[f(x)=1-x+{{x}^{2}}-{{x}^{3}}+...-{{x}^{15}}+{{x}^{16}}-{{x}^{17}}=\frac{1-{{x}^{18}}}{1+x}\] \[\Rightarrow f(x-1)=\frac{1-{{(x-1)}^{18}}}{x}\] Therefore, required coefficient of \[{{x}^{2}}\]is equal to coefficient of \[{{x}^{3}}\] in \[1-{{(x-1)}^{18,}}\]which is given by \[^{18}{{C}_{3}}=816\].You need to login to perform this action.
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