Answer:
[tex]\sqrt{7}[/tex]
Step-by-step explanation:
Using the rule of radicals
[tex]\sqrt{\frac{a}{b} }[/tex] ⇔ [tex]\frac{\sqrt{a} }{\sqrt{b} }[/tex]
[tex]\frac{\sqrt{21} }{\sqrt{3} }[/tex] = [tex]\sqrt{\frac{21}{3} }[/tex] = [tex]\sqrt{7}[/tex]
