\text{ধরি,} \sqrt{-8 - 6\sqrt{-1}} = x \\
\text{বা, } x^2 = -8 - 6\sqrt{-1^2} = -8 - 6i \\
\text{বা, } x^2 = 1 - 6i - 9 = 1 - 6i + 9i^2 \\
\text{বা, } x^2 = (1 - 3i)^2 \therefore x = \pm (1 - 3i) \\
\therefore \text{নির্দিষ্ট বর্গমূল } = \pm (1 - 3i) \text{ (Ans.)}
