remember some basic rules
[tex] \frac{x^m}{x^n}=x^{m-n} [/tex]
and
[tex]x^ \frac{m}{n}= \sqrt[n]{x^m} [/tex]
so
[tex] \frac{x^\frac{1}{2}}{x^\frac{2}{7}}=x^{\frac{1}{2}-\frac{2}{7}} [/tex]
1/2-2/7=
7/14-4/14=
3/14
[tex] x^{\frac{1}{2}-\frac{2}{7}}=x^{\frac{3}{14}} [/tex]
[tex]x^ \frac{3}{14}= \sqrt[14]{x^3} [/tex]
