first off, let's convert 0.25 to a fraction, notice, it has two decimals, therefore, we'll use two zeros on the denominator, two decimals, two zeros, thus,
[tex]\bf 0.\underline{25}\implies \cfrac{025}{1\underline{00}}\implies \cfrac{25}{100}\\\\
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\sqrt{0.25}\implies \sqrt{\cfrac{25}{100}}\implies \sqrt{\cfrac{5^2}{10^2}}\implies \cfrac{5}{10}\implies \cfrac{1}{2}[/tex]
