A dont understand how the step highlighted in red came about. How did the $\displaystyle 3 $ become $\displaystyle 3^2$ and the $\displaystyle 3^2$ become $\displaystyle 3^4$? And, also, how did the $\displaystyle 3^\frac{1}{3}$ before $\displaystyle (1+\frac{y^2}{3})^\frac{1}{3}$ come about when changing the form of $\displaystyle (3+y^2)^\frac{1}{3}$?