ANSWER
The radical form of the expression
[tex] {a}^{ \frac{m}{n} } = \sqrt[n]{ {a}^{m} } [/tex]
Note that
[tex]n = 2 \: or \: m = 1[/tex]
are not written explicitly. However, greater values are written explicitly.
So, for [tex] {2}^{ \frac{1}{2} } [/tex]
[tex] n=2, m=1[/tex]
This implies that, we will just write
[tex] {2}^{ \frac{1}{2} } = \sqrt{2} [/tex]
for [tex] {2}^{ \frac{2}{3} } [/tex]
[tex] n=3, m=2[/tex]
This implies that,
[tex] {2}^{ \frac{2}{3} } = \sqrt[3]{ {2}^{2} } [/tex]
Similarly,
[tex] {3}^{ \frac{3}{2} } = \sqrt{ {3}^{3} } [/tex]
[tex] {3}^{ \frac{1}{3} } = \sqrt[3]{ {3}} [/tex]