[tex](8 y^{6})^{ \frac{1}{3} [/tex]
To simplify the fraction exponent you can third root the equation:
[tex] \sqrt[3]{8 y^{6}} [/tex]
To simply from there: The cube root of 8 is 2. 6 cannot be evenly simplified so it stays as it is.
[tex]2 \sqrt[3]{ y^{6}} [/tex]
Hope this helps