Respuesta :

Answer: √5-2.

Step-by-step explanation:

[tex]\sqrt{9-4\sqrt{5} }=\\\\ \sqrt{5+4-2*2*\sqrt{5} } =\\\\\sqrt{(\sqrt{5})^2-2*\sqrt{5}*2+2^2 } =\\\\\sqrt{(\sqrt{5}-2)^2} =\\\\|\sqrt{5} -2|=\\\\\sqrt{5} -2[/tex]