if a=2-1.73 then (a-1/a)^3=?

$\mathrm{As} \mathrm{the} \mathrm{value} \mathrm{of} \sqrt{3} \mathrm{is} 1.73, \mathrm{so} \mathrm{we} \mathrm{can} \mathrm{write} \mathrm{a} = 2-\sqrt{3}$
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