Question

3£®ÏÂÁмÆËãÖУº¢Ù$\sqrt{\frac{-9}{-25}}$=$\frac{\sqrt{9}}{\sqrt{25}}$=$\frac{3}{5}$£¬¢Ú$\sqrt{\frac{b}{a}}$=$\frac{1}{a}$$\sqrt{b}$£¬¢Û$\sqrt{2\frac{1}{4}}$=$\sqrt{2}$+$\sqrt{\frac{1}{4}}$=$\frac{1}{2}$$\sqrt{2}$£¬¢Ü$\sqrt{\frac{4y}{27{x}^{2}}}$=$\frac{1}{9x}$$\sqrt{3y}$£¬ÍêÈ«ÕýÈ·µÄ¸öÊýÊÇ£¨¡¡¡¡£©

• A£® 2
• B£® 1
• C£® 4
• D£® 3

Answer 1

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½â´ð ½â£º£º$\sqrt{\frac{-9}{-25}}$=$\frac{\sqrt{9}}{\sqrt{25}}$=$\frac{3}{5}$£¬ËùÒÔ¢ÙÕýÈ·£»
$\sqrt{\frac{b}{a}}$=$\sqrt{\frac{ab}{{a}^{2}}}$=$\frac{\sqrt{ab}}{|a|}$£¬ËùÒÔ¢Ú´íÎó£»
$\sqrt{2\frac{1}{4}}$=$\sqrt{\frac{9}{4}}$=$\frac{3}{2}$£¬ËùÒÔ¢Û´íÎó£»
$\sqrt{\frac{4y}{27{x}^{2}}}$=$\sqrt{\frac{12y}{81{x}^{2}}}$=$\frac{2\sqrt{3y}}{9|x|}$£¬ËùÒԢܴíÎó£®
¹ÊÑ¡B£®

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