Answer:
[tex]\dfrac{9}{100}=0.09\ or\ \dfrac{9}{10}=0.9[/tex]
Step-by-step explanation:
[tex]\sqrt{a}=b\iff b^2=a\ for\ a\geq0\ and\ b\geq0\\\\\text{We have}\ \sqrt{81}:\\\\\sqrt{81}=9\ because\ 9^2=81.\ \text{Therefore}\\\\\dfrac{\sqrt{81}}{100}=\dfrac{9}{100}\\\\\text{If is}\ \sqrt{\dfrac{81}{100}},\text{then:}\\\\ \text{Use}\ \sqrt{\dfrac{a}{b}}=\dfrac{\sqrt{a}}{\sqrt{b}}\\\\\sqrt{\dfrac{81}{100}}=\dfrac{\sqrt{81}}{\sqrt{100}}=\dfrac{9}{10}=0.9\\\\\sqrt{81}=9\ because\ 9^2=81\\\sqrt{100}=10\ because\ 10^2=100[/tex]