A) - 20
B) 20
C) 30
D) - 30
Correct Answer: A
Solution :
In the expansion of \[{{\left( x-\frac{1}{x} \right)}^{6}}\], the general term is \[^{6}{{C}_{r}}{{x}^{6-r}}{{\left( -\frac{1}{x} \right)}^{r}}{{=}^{6}}{{C}_{r}}{{(-1)}^{r}}{{x}^{6-2r}}\] For term independent of \[x,\,\,6-2r=0\Rightarrow r=3\] Thus the required coefficient\[={{(-1)}^{3}}{{.}^{6}}{{C}_{3}}=-20\].
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