Respuesta :

[tex]\sqrt{90}=\sqrt{9\times10}\\--------------------\\use\ \sqrt{a\times b}=\sqrt{a}\times\sqrt{b}\\--------------------\\=\sqrt{9}\times\sqrt{10}=3\times\sqrt{10}=\huge\boxed{3\sqrt{10}}[/tex]
TSO
[tex] \sqrt{90} = \sqrt{9 \times 10} = \sqrt{9} \times \sqrt{10} = 3 \times \sqrt{10} =3 \sqrt{10} [/tex]

Using this formula:
[tex] \sqrt{a \times b} = \sqrt{a} \times \sqrt{b} [/tex]

Hope that helps :)