Răspuns:
[tex] \frac{12}{ \sqrt{12} } = \frac{12}{2 \sqrt{3} } [/tex]
[tex] \frac{21}{28} = \frac{21}{4 \sqrt{7} } [/tex]
[tex] \frac{ \sqrt{40} }{18} = \frac{4 \sqrt{10} }{2 \times 9} = \frac{2 \sqrt{10} }{9} [/tex]
[tex] \sqrt{2 \frac{1}{6} } = \sqrt{ \frac{13}{6} } [/tex]