Răspuns: 0,009
Explicație pas cu pas:
[tex]\displaystyle \sqrt{8,1 \ \cdot \ 10^{-5} } = \\\\\displaystyle \sqrt{\frac{81}{10} \ \cdot \ \frac{1}{10^{5} } } \ = \\ \\\displaystyle \sqrt{\frac{81}{10^{6} } } \ = \\\\\displaystyle \frac{9}{10^{3} } \ = \\\\\frac{9}{1000} \ = \\ \\\boxed{ 0,009}[/tex]