Coefficient of ${x^2}$ in the expansion of ${\left( {x - \frac{1}{{2x}}} \right)^8}$ is
Coefficient of ${x^2}$ in the expansion of ${\left( {x - \frac{1}{{2x}}} \right)^8}$ is
- A
$\frac{1}{7}$
- B
$\frac{{ - 1}}{7}$
- C
$-7$
- D
$7$
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